







A function which is onto but not onetoone 
20170416 

From Avinash: Define a function f(x):N>N which is onto but not oneone.Where N is set of natural numbers. Answered by Penny Nom. 





I was wondering what xy means. 
20150930 

From Eric: I was wondering what xy means. My two things I think it means are the two digits of x and y or x times y. thanks for your time,
Eric Answered by Penny Nom. 





Why is the area of square not conserved when it changes to a rhombus? 
20150628 

From shubham: Why is the area of square not conserved when it changes to a rhombus, both have equal sides still rhombus have less area than square.?? Answered by Penny Nom. 





The number of possible musical notes using an nkey instrument 
20150504 

From Farihin: Lets say that i have keys, and each key is for notes of a musical instrument,
So i wanted to find out the number of notes i can get for a certain number keys,
of course in the form of an equation. Notes can use as many keys, it can use 1, or 2, or 3, or even 100.
Notes in real life is not as such, but ignore reality.
I tried doing this but i can't seem to find a formula for it.
For example, i have 4 keys, say A, B, C, and D.
so, for notes that uses one key are 4, which is A, B, C, and D themselves.
for notes that uses two keys are 6,
AB, AC, AD, BC, BD and CD.
for notes that uses three keys are 4,
ABC, ABD, ACD and BCD.
lastly for notes that uses all four keys is 1, ABCD.
So, the total will be 4+6+4+1=15#
The nth term for the first equation is n, the second is [(n^2)n]/2
the third and the fourth, i don't know but the final answer should be like,
n + [(n^2)n]/2 + [3rd] + [4th]
Sorry for the long question though... Answered by Penny Nom. 





Exponential notation 
20141127 

From Jaqui: May sound super easy, but how would you SHOW that you simplified
3x3 to the power of 2 (the little 2)?
thank you!
Jaqui Answered by Penny Nom. 





What does y= f(x) actually mean? 
20131231 

From John:
I don't understand how to pick coordinates for y=f(x).
I took a look at your answer to a previous question here:
http://mathcentral.uregina.ca/QQ/database/QQ.09.00/monica2.html
What does y= f(x) actually mean? Answered by Penny Nom. 





Matrices 
20131110 

From Ricky: Why must we have brackets around matrices. Why don't we just neatly write an array of entries crosswise and up and down to indicate a particular matrix? Answered by Chris Fisher. 





Notation for the second derivative 
20120206 

From Shafira: In all math textbooks, it is written that d/dx ( d/dx) (y)= d2y/dx2. Why do they write it as d2y/dx2, not as d2y/d2x2? Answered by Robert Dawson. 





What does 2xy mean? 
20111207 

From dana: I don't know what is 2xy what does that mean? is it 2x+2y or 2x times y
Please help! thank you for your time!! :) Answered by Penny Nom. 





Exponential form? 
20110830 

From Emily: I have a 6th grader that needs to find out what is the exponential form of 461,885,811 Answered by Penny Nom. 





Exponential form 
20110823 

From kiara: The African bush elephant is the largest land animal and
weighs about 8 tons . Write the amount in exponential form . Answered by Robert Dawson. 





Set notation 
20110110 

From Ron: The question asked in a handout:
8k  5 < 35, keI
I believe the answer to k is 5. But what does the k e(E) I mean in this? Answered by Harley Weston. 





What is the average speed? 
20100921 

From Cindy: A boat travels downstream m nautical miles at d knots. It travels upstream m nautical miles at u knots. What is the average speed for the entire trip? Answered by Penny Nom. 





(x+1)(x+2)(x+3)/(x+1)(x+2) 
20100519 

From Nazrul: Simplify : (x+1)(x+2)(x+3)/(x+1)(x+2)
Which answer is correct:
(i) x+3
(ii) (x+2)^2(x+3)
Please help me. Answered by Harley Weston. 





divide the product of 'x' and '3y' by '2z' 
20100119 

From shradheya: write all fall using variable ,number, and basic operation
1. divide the product of 'x' and '3y' by '2z'. Answered by Penny Nom. 





Exponential form 
20090831 

From cecil: what is the exponent form 564000? Answered by Stephen La Rocque and Harley Weston. 





The area of a rectangle 
20090821 

From roxanne: the dimensions of the rectangle: 3x length and 4x width. What is the area of the rectangle in square units? Answered by Penny Nom. 





2+6+12+20+30+42 
20090424 

From fredy: what is the sigma notation for the series 2+6+12+20+30+42? Answered by Stephen La Rocque. 





Find the product of 2^35 and 5^38 in sci. notation. 
20080803 

From Peter: I am preparing for a competition and a lot of the noncalculator problems are like find the product of 2^35 and 5^38 in sci. notation. How would you do that? Answered by Penny Nom. 





Sum of Digits 
20080724 

From Warren: If 100^2525 is written in decimal notation, what is the sum of digits? Answered by Penny Nom. 





A tangent to a curve through a point not on the curve 
20080723 

From Carter: How does one find the tangent points on a curve, given only the curve's function
and the xintercept of that tangent line?
i.e. Find the point(s) on the curve y = (x^2) + 1, where the tangent line passes
through the point (2, 0).
I know that there will be two such points, one where y is very close to 1, and the
other point where y is a large negative number. However, I do not recall how to
figure out the tangent line equation given a single intercept and solving to find the
tangent points. Answered by Penny Nom. 





Exponential form 
20080703 

From Kent: How to write 8 365 005 106 in expanded and exponential form? May I request you also to explane how does it solve. Answered by Stephen La Rocque. 





Scientific notation 
20080611 

From ASTRID: how can you solve the following problem...
the mean distance between the sun & plut0 is about 3,700,000,000
miles. write this distance in scientific notation? Answered by Penny Nom. 





Sigma notation 
20080106 

From jamelia: what is this word problem in sigma style i am so lost at this point my first time ever attempting this subject
1+2+3+4+5 Answered by Penny Nom. 





Exponential form 
20071130 

From Sasha: How do I write the number 127398 in exponential for? Answered by Penny Nom. 





Exponential form: x^y 
20070622 

From Kishor: whats the easy way to calculate X raised to Y where y is much greater than x. Answered by Stephen La Rocque. 





A thousand, is it M or K? 
20070501 

From Larry: I have heard that Million is annotated as MM. But Ihave heard two answers for Thousands (K, M). Which is correct? Answered by Penny Nom. 





Scientific notation 
20070417 

From Cynthia: Hi I was wondering if their was a shorter way to figure out this problem...
The answer has to be in scientific notation.
A machine in a soft drink bottling factory caps 3 bottles per second.
How many bottles can it cap in 15 hours?
3,600 (forgot how I got that) multiplied by 15= 54,000
54,000 multiplied by 3 = 16,2000
answer 1.6times 10^5 Answered by Stephen La Rocque. 





Scientific notation 
20070305 

From mackenzie: How would you answer this question? Write 0.000661 in scientific notation? Answered by Sara Ulmer. 





y = 5 x  3 
20070110 

From Richard: Question is the function y = 5 x  3 for the given value of x 7 , 1 or 4 Answered by Stephen La Rocque and Penny Nom. 





Sigma notation 
20061205 

From Marie: how do i get this in sigma notation...i only need an explanation 1^2 + (2+3)^2 + (4+5+6)^2 + (7+8+9+10)^2.... Answered by Penny Nom. 





100, 000 or 100 000 
20051121 

From Jacqui: I am a parent of a grade 6 student and need to confirm that commas are no longer used when writing numbers (the Canadian method). For example, how do you write one hundred thousand? 100, 000 or 100 000 Answered by Diane Hanson and Harley Weston. 





The series from i=1 to n :ai 
20040818 

From Ken: a.) Explain the difference between
the series from i=1 to n :ai
and the series j=1 to n :aj
b.) Explain the difference between
the series from i=1 to n:ai
and the series from i=1 to n :aj Answered by Penny Nom. 





When is the limit of f(x) undefined? 
20040803 

From Nicolasa: When is the limit of f(x) undefined? Answered by Penny Nom. 





The horizontal fraction bar 
20040527 

From Kashia: What is the name of the bar that separates a numerator and that denominator? Answered by Penny Nom. 





Notation 
20030915 

From Kim:
Question: i have a couple of questions 1. write in standard form a)4x2x8 b) 5 to the power of 4 . . . Answered by Penny Nom. 





Scientific notation 
20030320 

From A student: what is one millionth times one thousand in scientific notation. Answered by Penny Nom. 





A rope trick 
20021205 

From Jerry: My name is Jerry and I am a math teacher at the secondary school level in the greater Toronto area. I posed the following problem to my enriched grade 10 math class that I found in the book called "Mathematics and the Imagination" by William Kastner. According to the author, it is posible for two people linked to each other with two ropes around their hands, to separate themselves without letting go of the rope. The students had lots of fun trying to accomplish this problem using skipping ropes from the Phys Ed department, but with no success. Answered by Penny Nom. 





Exponential notation 
20021019 

From Ivy: I understand how to figure out for example 4 to the power of 3,what I don't understand is how to figure it out using both negative numbers and negative exponents,as an exaple 4 to the power of 6 and what makes this different that (5) to the power of 7,please help me if you can.I am an adult taking correspondence and finding it quite frustrating. Answered by Penny Nom. 





Inequalities 
20011113 

From Pat: When writing the solution to an inequality, why is the solution written in set notation? {x/ } Answered by Penny Nom. 





Exponential form 
20010606 

From A student: Hello can u please answer my question what is the exponent form of 8x8x8x8 Answered by Penny Nom. 





Repeating decimal notation 
20001231 

From Clarende Duby: I have seen single repeating decimals for ex. 1/3 = 0.3 with the dot above the 3 to represent the repeating decimal. Then, there is the more common form of the bar over the top of the repeating number or group of numbers (called the period?). Which notation is correct? Answered by Penny Nom. 





Scientific notation 
20001212 

From Guy: How do I express 1.000.000 in scientific notation? Answered by Harley Weston. 





Notation 
19990903 

From Judy Gray: My name is Judy Gray. I guess the level on this would be about middle school, and I am an other!! I've been out of school for alot of years. I have a couple of questions, I guess.  What does an equal (=) with a slash through it mean? I put intersects, but I think I'm wrong.
 What is the symbol of a small n? Only the symbol is wider. Example: If A = {1.2} B = {2,3} then what is A (n) B? Can you make sense out of that?
 What is the equation of the yaxis?
Answered by Penny Nom. 





Scientific Notation 
19981007 

From R. Pierce: Help! How do you express the following numbers in scientific(exponential)notation:0.00036 and 2998000000. I understand how to solve them if it was an equation, but this is confusing me. Please help me answer my questions. Thank you. Answered by Harley Weston. 





Repeating decimals 
19960909 

From Alice: What is the line called that is placed over the decimal to show that it is infinitely repeating? Answered by The Centralizer. 





La valeur absolue 
20080209 

From Elodie: que signifie la notation x entre 2 traits verticaux? Answered by Claude Tardif. 

