







Successive Differences 
20170406 

From Twaha: Please find the equation of the sequence 1 2 4 7 11 16 22 Answered by Penny Nom. 





A pattern rule for a sequence 
20161028 

From Grace: Here's a Grade 7 question, we need to find the pattern rule:
1  1
2  3
3  6
4  10
......
It may involve exponents, but we can't seem to figure it out.
thank you.
Grace. Answered by Penny Nom. 





A sequence 
20160105 

From Mia: the next three terms in each sequence. 0.4, 0.54, 0.68, 0.82, Answered by Penny Nom. 





Distance as a function of acceleration 
20130710 

From Tom: If you start at a stoplight and your acceleration is 16t  t^2, how far have you gone after 8 seconds? Answered by Penny Nom. 





Possible soccer scores 
20121009 

From Riaan: Good day, I would like to know all the possible scores for a set of 5 soccer matches with no more than 5 total goals being scored in any match.
Bearing in mind that there are three outcomes to every match. Win, Lose or Draw.
Could you please help me with this?
Kind regards
Riaan
South Africa Answered by Penny Nom. 





Uniform acceleration 
20111206 

From Android: At a certain instant, two cars A and B are 2000 ft apart. At this instant, car A is traveling at 15 miles/hr. and accelerating at 3 ft/s^2 while B is moving towards A at 30 miles/hr. and an acceleration of 2 ft/s^2.
Find the ff:
a.) The possible time of their collusion in minutes.
b.) The distance in ft. each has traveled before collusion. Answered by Penny Nom. 





A mythical soccer ball 
20111027 

From Joel: We've been working on this problem diligently and can't seem to come up with the answer book's answer. We think it may be wrong, yet want to check it with an expert. Here goes.
The school's new soccer balls are covered with 64 regular hexagonal panels. Each hexagon measures 2 inches between opposite corners and 1.5 inches between opposite sides. What is the total surface area of the soccer ball? Answered by Robert Dawson and Lorraine Dame. 





Fibonacci and induction 
20100712 

From James: I'm trying to prove by induction that F(n) <= 2^(n1)
where f(1)=f(2)=1 and f(k)=f(k1)+f(k2) for k >=3 is the Fibonacci sequence Answered by Stephen La Rocque and Tyler Wood. 





Body measurements 
20100406 

From Amirul: Recently I'm proposing my research question to my teacher for my extended essay. I'm an IB student.
My research question is regarding the estimation of human in buying trousers through reference of neck. What does the relation between the diameter of the neck and the diameter of the waist?
I want to see how far does the estimation theory is true for different type of people with different BMI(body mass index)..
But teacher said that it is golden ratio...so nothing interesting... =(
really??? But i search on net.... state that my idea seems do not have any relation with the golden ratio so far..... i just want ask you... am I able to perform in my extended essay if i continue with this research question?? Answered by Robert Dawson. 





The nth derivative of x^(n1) log x 
20100310 

From shambodeb: This is a successive differentiation problem by Leibnitz theorem
If y = x^{n1} log x ; Proof nth derivative y^{(n)} = (n1)!/x Answered by Harley Weston. 





The test for some disease is 99% accurate 
20100224 

From baaba: Assume that the test for some disease is 99% accurate. If somebody tests positive for that disease, is there a 99% chance that they have the disease? Answered by Chris Fisher. 





Investing in multiple accounts 
20090626 

From Kenneth: Hello:
If an investor has $1000.00 to invest in multiple accounts, and he
wants a total return of 4%, is there one calculation that can be used
to determine what these amounts could be even though there may be
numerous amounts used as answers for most of the following examples?
For example,
Invest $1000.00 @ 2% and 5% for total return of 4%.
Invest $1000.00 @ 2%, 3% and 5% for total return of 4%.
Invest $1000.00 @ 2%, 3%, and 5% for total return of 4%.
Invest $1000.00 @ 2%, 3%, 4% and 5% for total return of 4%.
etc. Answered by Robert Dawson. 





Accuracy of Data 
20090625 

From Bill: If say, a predictin is 20 and the actual is 35 how do you work out the accuracy of the prediction Answered by Janice Cotcher. 





Successive differences 
20090618 

From Jonathan: I'm trying to find the next number sequence for this equation: 1 11 35 79 149 251, my problem is that I worked it out and ended up with a single number 17. What am I doing wrong. Thank you for any help. Answered by Robert Dawson and Penny Nom. 





Cubic centimeters and ounces 
20090206 

From Dawn: 1 syringe contains 5.5cc of medicine & cost $13.50
1 2 oz bottle of medicine cost $17.50
How many cc's in 2 oz, & which is the better deal? Answered by Stephen La Rocque. 





A falling object 
20090201 

From Tamara: We drop an object from rest (i.e. its initial spped is zero. It is falling freely toward the ground. What will be its speed after 5 seconds of falling? Answered by Penny Nom. 





What will be its speed after 10s? 
20090201 

From Tamara: An object has an initial speed of 5 m/s and is accelerating with 2 m/s2 (m/s squared) acceleration. What will be its speed after 10s? Answered by Penny Nom. 





Jon's bank account 
20090103 

From Abigail: Hi, i have an exam soon (monday =[ )
in my revison book, it shows two peoples bank accounts and then it says
"write a formula to show the balence of Jon's bank account after n weeks of 2003"
this is the table show
Jon's Bank account
Weeks 
Week 1 
Week 2 
Week 3 
Week 4 
Week 5 
Balance(£) 
970 
1035 
1100 
1165 
1230 
Answered by Penny Nom. 





Topsoil on a soccer field 
20081202 

From rita: a park foreman decides that a soccer field needs 4 inches of topsoil. soccer field is 100 feet by 250 feet.
1 truckoad is 5 cubic yards. how many truckloads do we need to order. i keep confusing myself with formulas. please explain the steps to me
thank you Answered by Penny. 





3,6,10,15,and 21 
20080928 

From jarred: i am currently stumped on a math project that requires me to find out the recursive formula for a sequence of numbers. the numbers in the sequence are 3,6,10,15,and 21. Thank you for your time. Answered by Walter Whiteley. 





Art and Integers 
20080917 

From pamela: how do artists use integers? Answered by Janice Cotcher. 





How accurate is the following calculation? 
20080903 

From Craig: Given that these numbers are only accurate to 2 decimal places, how accurate is the following calculation?
1.73  2.16 + 0.08 + 1.00  2.23  0.97 + 3.02 = 0.47
How do I work out the accuracy? Answered by Penny Nom. 





Eccentricity of an Elliptical Orbit 
20080820 

From Gina: A satellite has an elliptical orbit around the earth with one focus at the earth’s
center, E. The earth’s radius is 4,000 miles. The highest point that the satellite is
from the surface of the earth is 800 miles, and the lowest is 200 miles.
What is the eccentricity of the satellite’s orbit? Answered by Janice Cotcher. 





Time with NonUniform Motion 
20080721 

From jenina: An unmarked police car, travelling a constant 95km/h, is passed by a speeder travelling 145km/h. precisely 1.00s after the speed passes, the policeman steps on the accelerator. If the police car’s acceleration is 2.00m/s², how much time elapses after the police car is passed until it overtakes the speeder (assumed moving at constant speed)? Answered by Janice Cotcher. 





What is the account value after 3 years? 
20080710 

From Carlos: Question
Suppose that you deposited $3,000 at the beginning of each year for three years in a savings account earning 4%. What is the account value after 3 years (approx)?
a. 9,120
b. 9,211
c. 9,739
d. 9,989 Answered by Penny Nom. 





Throwing a ball on the moon 
20080521 

From leria: equation for motion of moon is h=2.67t^2 + vt + s
equation for earth h=16t + vt + s
Suppose you are on an outpost on the moon and Jan is back on Earth. Both people toss a ball from a height of 96 feet with an initial velocity of 16 feet per second. How much longer will your ball stay in motion on the moon than Jan's on the earth?
Math Central,
I'm having a difficult time understanding which numbers to plug into the formula. Answered by Stephen La Rocque. 





The sum of the squares of the fibonacci numbers 
20080427 

From Thomas: Hey I have a question for a research topic that our teacher set us, It is regarding the sum of the squares of the fibonacci numbers.
The question says describe the pattern that exists and write a general formula that describes the relationship illustrated above.
I can see the pattern that is occurring but i cannot put this into a general formula.
Any help would be appreciated.
Thanks Tom Answered by Victoria West. 





At what value of t is the maximum acceleration? 
20080425 

From Mary: Velocity of a function (which is the first derivative of its position) is defined over the interval 0 to 12 using the following piecewise function: v(t)=1 from 0 to 4, v(t)=x5 from (4 to 8 and v(t)=x+11 from (8 to 12. At what value of t is the maximum acceleration? Answered by Stephen La Rocque. 





1, 1, 2, 3, 5, 8, 13, ___ ___ ___ 
20080313 

From Karen: What is the rule for the following pattern, and what would come next?
1, 1, 2, 3, 5, 8, 13, ___ ___ ___ Answered by Penny Nom. 





Two points moving on a straight line 
20080306 

From laura: Particle A travels at constant speed of 1.0ms1 in straight line, passing particle B, at which time particle B beings traveling with constant acceleration of 0.2ms2 until reaching Particle A.
What equations represent the displacement of particle A and particle B measure from the point they first pass?
How long does it take for particle B to catch up with particle A?
What is the speed of particle B when reaching particle A?
What distance have both particles traveled from where they first pass to where they meet again?
Calculate the displacement of both particle A and B at 2 second intervals between t=0s and t=12s? Answered by Stephen La Rocque and Penny Nom. 





Fibonacci numbers 
20080130 

From Beth: You've answered a question for a Linda Bach on Oct. 25, 1999 that has to do with a pet rabbit and stairs. (Working Backwards) We were wandering if there is a formula we can use to plug the numbers in? My 7th grader got that exact same problem. I've spent several hrs trying to come up with a formula. I've tried the combinations formula, the Pascal's triangle and the Permutations formula. It seems like it is something real close to those, but can't quite get anything to work. What kind of formula would work for finding the outcome of this problem? Thanks so much for your help. Beth Answered by Penny Nom. 





How far from the corner will the police catch the car? 
20080127 

From Joel: A car is going down the road at a speed of 90km/h in a 50km/h zone.
As the car passes a corner, a police cruiser sitting there notices it. Five
seconds later the cruiser begins accelerating at 5.0m/s squared.
Assuming that he is able to maintain this acceleration, how far from the
corner will the police catch the car? How fast will the cruiser be going? Answered by Stephen La Rocque. 





The volume of a soccer ball 
20071125 

From Ria: A student of me is working on a paper about soccer and math/physics. He wants to calculate the volume of the ball, which is composed of 5 and 6sided pyramids. We are looking after a formula to express the volume of these pyramids in function of the radius of the ball (and if possible how we can derive this formula). Afterwards we'll try to calculate the difference with the volume of a sphere with radius r. Answered by Stephen La Rocque. 





What number best completes the series? 
20071112 

From Grace: What number best completes the series?
2 3 7 13 27 ____ Answered by Stephen La Rocque, Penny Nom and Harley Weston. 





Constantly accelerated motion 
20071029 

From Priyanka: A, B and C are three points lying in that order on a straight line. A body is
projected from B towards A with speed 3 m/s. The body experiences an
acceleration of 1 m/s^2 towards C. If BC =20 m, find the time taken to reach C and
the distance travelled by the body from the moment of projection until it reaches C. Answered by Stephen La Rocque. 





The nth term 
20071018 

From shannon: Ok , what i am having problems with is the nth term. I get how the numbers come together, but i am having trouble with finding the nth term. Answered by Penny Nom. 





0,1,2,3,6,11,20,37,68... 
20071016 

From Pat: Describe the rule for this pattern:
0,1,2,3,6,11,20,37,68...
Thanks Answered by Penny Nom. 





Angle of depression to a football 
20070815 

From Tosin: The angle of depression to a football from the top of building 10m high
is 17 degrees. Find the distance of the ball from the foot of the building. Answered by Stephen La Rocque. 





Vehicle collision 
20070731 

From Tania: If a driver falls asleep at the wheel of a newer model car and slams into
the rear of a parked classic mustang (28603280lb) and the parked car
is thrown 100 ft across the street, what would be the minimum speed
required by the newer car in order to move the mustang? Answered by Penny Nom. 





How fast was he going? 
20070603 

From Mary: if a motorcycle left a 63 foot skid mark before hitting a car how fast was he going ? Answered by Penny Nom. 





The second derivative 
20070414 

From Gerry: In mathematical context,what do you understand by the term "Second Derivative" Answered by Penny Nom. 





Acceptance sampling 
20070329 

From Katrina: The Medassist Pharmaceutical Company recieves large shipments of
asprin tablets and uses this acceptance sampling plan: Randomly select
and test 24 tablets, then accept the whole batch if there is only one or
none that doesnt meet the required specifications. If a particular shipment
of thousands of asprin tablets actually has a 4% rate of defects, what is
the probability that this whole shipment will be accepted? Answered by Penny Nom. 





Seven digit account numbers 
20070309 

From Miranda: Account numbers for the Central Oil Company consist of seven digits. If the first digit cannot be 0, how many account numbers are possible? Thank you so much!!! Answered by Penny Nom. 





How long does she have to get out of the way? 
20070223 

From Sharon: How do I solve this? The height h (in feet) of an object that is dropped from the height of s feet is given by the formula h = s  16t^2 , where t is the time the object has been falling. A 6 foot tall woman on a sidewalk looks directly overhead and sees a window washer drop a bottle from the 6 story. How long does she have to get out of the way? Round to the nearest tenth. (A story is 12 feet.) Answered by Penny Nom. 





Acceleration 
20070220 

From thomas: Don't know if this service still exists. ACCELERATION CALCULATION initial vel 0km/hr final vel 24km/hr time 3s Answered by Stephen La Rocque. 





A person jumps from the roof of a house 
20070213 

From Jessie: A person jumps from the roof of a house 3.9m high. When he strikes the ground below, he bends his knees so that the torso decelerates over an approximate distance of 0.70m. If the mass of his torso (excluding legs) is 42kg, find a) his velocity just before his feet strike the ground , and b) the average force exerted on his torso by his legs during deceleration.
Please provide calculations and answers for comparison. Answered by Stephen La Rocque. 





Find the next 3 terms of the sequence 
20070207 

From rose: find the next 3 terms of the sequence 2,3,9,23,48,87 Answered by Penny Nom. 





Freefalling objects 
20070125 

From Patricia: How long will it take a stone dropped from atop a 1000meter tall building to reach the ground? Answered by Stephen La Rocque. 





Throwing a stone downwards 
20070112 

From Momo: a stone is thrown vertically downward with an initial speed of 14m/s from a height of 65 m above the ground. A) how far does the stone travel in the first 2.0 s? B) what is the stone velocity just before it hits the ground? Answered by Stephen La Rocque. 





The Fibonacci sequence 
20061121 

From Ross: Let f0 = 0; f1 = 1,... be the Fibonacci sequence where for all n greater than or equal to 2 fn = fn1 + fn2. Let Q = (1+square root of 5)/2. Show that for all positive n greater than or equal to 0, fn less than or equal to Q^(n1). Answered by Penny Nom. 





Find the distance function s(t) given the acceleration function a(t) 
20061116 

From David: Find the distance function s(t) of the acceleration function: a(t)= sin(0.1t)/ cos^3(0.1t) Answered by Penny Nom. 





how many ounces are in 750 cc's. 
20061014 

From Not a teacher: how many ounces are in 750 cc's. Answered by Stephen La Rocque. 





The interior angles of a right triangle 
20060520 

From Greg: I am wondering if there is a way to figure out the interior angles of a right triangle if we know ONLY the side lengths, and the trick is, we CANNOT use arctangent! Answered by Leeanne Boehm and Penny Nom. 





The radius of a soccor ball 
20060505 

From Jacqui: A soccer ball is made up of hexagons and pentagons with the same side lengths.
A manufacturer wants to produce a ball of certain diameter. The questions that follows is what side length for the polygons will produce a ball of certain diameter. Answered by Chris Fisher. 





Reverse percentage 
20060419 

From Mike: How would I calculate a reverse percentage?
Let me give you an example. I have two values that calculate to a success rate of 93.32. Total=1546051 Failures=103302. (1546051103302)/1546051=93.32% success.
Now how much would I need to increase the total value to get the success up to 95%? Answered by Stephen La Rocque. 





The stair problem 
20051206 

From Arnold:
My daughter had me help her with some of her college math problems that require finding the pattern. The problem was the stair problem where you can climb either 1 step or 2 steps at a time. How many combinations are there to get to the 10th step. I found the data set that solves the answer to the question, but is there an equation that expresses the answer in terms of n?
1 2 3 4 5 6 7 8 9 10 stair number
1 2 3 5 8 13 21 34 55 89 number of possible combinations
Answered by Harley Weston. 





Velocity and acceleration 
20051027 

From Candace: When taking the integral of the position function, you get the velocity function, and the same for velocity to acceleration. So when you do each of these, you get a function. But when you integrate on a graph, you get an area under a curve. The area is un units squared where do the units go when you make it an equation? How can a function be an area? Answered by Harley Weston. 





How many ounces is 750 cc's? 
20050924 

From Michael: How many ounces is 750 cc's? Answered by Penny Nom. 





arccos(5/13) 
20050531 

From Kyle: I would like to know how to evaluate the problem of: Arccos 5/13. Answered by Penny Nom. 





A 4digit access code 
20050102 

From Missi: I need to find the 4 digit number to access my voice mail. These numbers will be 09 & numbers can be repeated. Could you provide me with a list of possibly combinations? If not, do you know anywhere that I could get a list of combinations so I don't have to write it all down? Answered by Harley Weston. 





Accelerating to the speed of light 
20040930 

From Lars: How long time would it take to accelerate up to the speed of light with an acceleration speed similar to 0100 seconds in 5 seconds? Answered by Penny Nom. 





130 cc. is ? 
20040820 

From Ayrn: 130 cc. is ?
I have to put 130cc. of petroleum in a bucket how much exactly is that?
Also 110 cc.?
I have to also put 110cc. wood alcohol in a bucket aswell! Answered by Penny Nom. 





A Fibonacci triangle 
20040425 

From Marcelle: Is it possible to construct a triangle with sides that are three consecutive Fibonacci numbers? Answered by Walter Whiteley. 





425 cc's of a saline solution 
20040330 

From Julie: 425 cc's of a saline solution is equal to how much in lbsweight?? Answered by Harley Weston. 





Ounces into cubic centimeters 
20040127 

From A student: how do you convert ounces into cubic centimeters? Ex: how does 12 oz. change into cc. Answered by Penny Nom. 





g on Mars 
20040122 

From RC: To measure the acceleration on Mars an object is dropped from a height of 160m. It takes 10s for this object to hit the ground. What is the value for g on Mars?g Answered by Penny Nom. 





Unusual occurances 
20040108 

From Martin: My wife and I have a question about the probability of something that happened to us a few years ago. So far, no one has been able to give me even an approximate answer. On my 32nd birthday, my wife and I went out to eat at local Japanese hibachi style restaurant. At the restaurant, couples/families are sat together around the hibachi where the cook performs a show. There was a fifteen minute or so wait, so my wife and I sat in the lounge waiting for our name to be called. When they called our names for the reservation, this is what happened. The first group called was the Martin family. Then they called the Francis family. We were the next family to be called, the Ashton family. My full name is Martin Francis Ashton! I think the odds of that happening to someone are very unlikely, but it did, and there is more. Next, we were all sat at the same table in that order, "Martin" family, "Francis" family, then us, the "Ashton" family. Again, it formed my full name! Answered by Penny Nom. 





A helicopter rises vertically 
20030902 

From Kate: A helicopter rises vertically and t seconds after leaving hte ground its velocity is given in feet per second by v(t) = 8t + 40 / (t+2)^{2} How far above the ground will the helicopter be after 3 seconds? Answered by Penny Nom. 





Fibonacci exam 
20030128 

From Mike:
My son will be participating in the national math contest. He is a grade 4 student but will be writing the Fibonacci exam for grade 5. He has been given last years exam for practice. Parents have been ask to assist for this part. I was therfore hoping for a little "inside" help on several questions with answers & short explanations. This with a would be greatly appreciated.(from last years exam)  With 3 weights, Mathusalem can weigh any object that has a weight which is smaller or equal to 13 kg, but that weighs a whole number of kilograms. He wants to weigh an object of 7 kilograms. To do so, he must place two of the weights on the left side of the scale, and the third one on the right side. Which one will he have to place on the right side
a)4 b)3 c)6 d)2 e)5  Mathilda uses a rectangular prisms to build stairs. The cross section of each prism is a square which has a side of 1 dm. Mathilda has already put in place 4 steps of a staircase that must have a height of 10 dm. When finished, the staircase will have a volume of 550 dm3. What will the width of the staicase in dm be?
a)10 b)55 c)11 d)1 e)100  The year 1991 was the last palindrome year of the second millennium. The year 2002 is the first palindrome year of the third millennium. Including 2002, how many palindrome years will there be, altogether, in the third millennium ?
a)8 b)2 c)10 d)182 e) 9 Greatly appreciated, Mike
Answered by Penny Nom. 





Calculations 
20021215 

From Mahdi: This problem is rather general, but it usually makes a lot of problems. I almost have no difficulty in math and physics questions, but unfortunately I'm not at all accurate in simple one or two digit calculation. I even sometimes make silly mistakes in simple sums like 7+4=12 or 4+5=11! Is there any effective way to reduce these mistakes? Answered by Walter Whiteley. 





Cubic centimeters 
20021107 

From Rita: Was in emergency room yesterdayMD aspirated 40cc of fluid from my kneewhat does a "cc" equate to? Answered by Penny Nom. 





Baseball, basketball and football 
20021008 

From Debbie: The school newspaper is interviewing 6th grade students to see what sports they follow regularly on TV. Of the 70 students interviewed; 40 enjoyed basketball; 40 enjoyed baseball; 40 enjoyed football; 20 enjoyed basketball and football; 22 enjoyed baseball and basketball; 27 enjoyed football and baseball; and 12 enjoyed all three sports. How many students out of the 70 interviewed didn't follow any one of the three sports? Answered by Leeanne Boehm, Penny Nom and Walter Whiteley. 





A good rule of thumb when driving 
20020613 

From Lisa: A good rule of thumb when driving is that you should be about one car length away from the car in front of you for every 10 miles per hour that you are travelling. Suppose you follow this rule perfectly (so you are exactly the correct distance away). You are waiting at a stop light with your front bumper just touching the car in front of you. The light turns green and the car in front accelerates at a constant rate "r". Calculate how you should accelerate in order to follow the rule. Answered by Penny Nom. 





Ounces and cubic centimeters 
20020530 

From Martin: How many ounces are in 600cc of liquid? Answered by Penny Nom. 





How many different account numbers are possible? 
20020418 

From Andrene: how many different account numbers are possible if the account numbers consist of a letter of the alphabet, followed by five numerical digits, and followed by another letter. Answered by Penny Nom. 





Successive differences 
20020120 

From Linsey: what is the rule for working out the formula for a sequence with three lines of difference? eg.
1, 3, 7, 15, 29
1st line differences: 2, 4, 8, 14
2nd line differences: 2, 4, 6
3rd line differences: 2, 2 Answered by Penny Nom. 





Squares of Fibonacci numbers 
20010424 

From Vandan: What discoveries can be made about the sum of squares of Fibonacci's Sequence? Answered by Penny Nom. 





A jogger 
20010312 

From Bill: At time t=0 a jogger is running at a velocity of 300 meters per minute. The jogger is slowing down with a negative acceleration that is directly propotional to time t. This brings the jogger to a stop in 10 minutes. a) write an expression for the velocity of the jogger at time t. b) what is the total distance traveled by the jogger in that 10minute interval. Answered by Harley Weston. 





Fibonacci 
20010228 

From Shona: We have been doing pattern finding with him, talking to a friend he mentioned the "Fibbinacci Series" ?, while I have tried to find a bit about it, how works etc.. what it is about, I have not really found out much, what I have I feel is way beyond him, but am still curious to know the basics of it myself. Would you be able to tell me in laymans language. Would be very much appreciated. Answered by Claude Tardif. 





Finding roots 
20010201 

From A student: My math problem is right now we are working on roots. I don't quite understand how to find the answer to the problems, i was wondering what is the easiest, and fastest way to find the answers to roots? Answered by Penny Nom and Claude Tardif. 





Fibonacci 
20001207 

From A student: Can you give me any info about Fibonacci?? Answered by Penny Nom. 





Gravity 
20000906 

From Robert Broomfield: If they dropped a 1lb object from 40,000 feet in the air, at what speed would it it the ground? Answered by Harley Weston. 





Fibonacci Numbers 
19991215 

From Gary Nelb: I'm doing a project on fibonacci numbers and I'm using different starting values and finding out if different starting values to see whether or not the ratios still get closer to phi. I was wondering, what numbers should I use. Should I use two of the same # like 2 and 2, or numbers like 1 and 2, or even something totally different. Answered by Denis Hanson. 





Finding a rule for a sequence 
19990217 

From Lindsey Masters: I'm doing a maths investigation and i have a sequence which goes: 13,16,25,32,45,56,73. Our teacher told us we have to find a rule by looking at the differences of the terms until we find a constant. The first differences are: 3,9,7,13,11,17. The differences of these are: ...... Please could you tell me how to work it out so that I could work out the rules of similar sequences. Answered by Penny Nom. 





Pay Phone Problem 
19980226 

From Shameq: Hi, I've been given a problem that I'm having some trouble with. I'd really appreciate any help. Here's the question (it's called the Pay Phone Problem) A pay phone will take only 10p, 20p, 50p, and £1 coins"(It's British). A woman has plenty of 10p and 20p coins. She has no other coins. She can put the coins into the pay phone in any order. INVESTIGATE the number of different ways, she could put the 10p and 20p coins into the pay phone. Answered by Penny Nom. 





A problem with arccos. 
19970609 

From Vanessa Chan: Prove: arc cos4/5 + arc cos (5/13) = arc cos (56/65) Answered by Harley Weston. 





Stairs 
19960212 

From Marianne and Carrie: How many ways can you run up a flight of stairs? Answered by Denis Hanson. 





Magic Square 
19951020 

From Marianne and Carrie: How can an 8 by 8 square have the same area as a 5 by 13 rectangle? Answered by Denis Hanson. 

