7 items are filed under this topic.
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Divisibility by 3 |
2018-11-20 |
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From Ray:
There is a rule that a number is divisible by 3 if the sum of its digits are divisible by 3 (for example, 81=8+1=9 {divisible by 3} and 33=3+3=6 {again, divisible by 3}) I know this works but I don't know why! Please help.
Answered by Penny Nom. |
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Some 6 digit numbers |
2012-10-23 |
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From Mason:
How many different 6 digit numbers can you make using the digits 1 ,2 5, 6, 7, and 9? How many of these six-digit numbers are divisible by 6?
Answered by Penny Nom. |
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Powers |
2010-10-20 |
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From dylan:
how do you write 20736 in exponential form .same for 1728 and 50625.
is there a formula to figure out how to express large know numbers in exponential form.
Answered by Penny Nom. |
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Divisibility by 3 |
2010-05-23 |
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From Cathleen:
To math central. I have to do a maths extension question that I don't understand. At first I thought I did.
It is about the dividing by three. In one part of the question, it asks me to show that the rule of division by three does not work for 23142 with a little 5 down the bottom.
What doe base 5 mean? We first thought that the little 5 down the bottom meant multiplying y the power of five.
Can you please tell me what it means so I can finish this question?
Answered by Penny Nom. |
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The sum of the digits of a number |
2008-06-23 |
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From Ben:
Question: Using mathematical induction, prove that if the sum of the digits of a number is divisible by three, then the number itself is also divisible by 3.
Answered by Penny Nom. |
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Divisibility rules |
2001-09-07 |
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From A student:
Why is it that when you add the digits of a number you can tell what the multiples of that number are. Example: 12131313111,
1+2+1+2+1+3+1+1+1=18,
therefore 12131313111 is divisble by 2, 9, 18, & 3 because those numbers are divisble by 18.
Answered by Penny Nom. |
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Divisibility by 3 |
2000-03-24 |
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From Pat Walsh:
W hy does it work when you add the digits of a number then divid by three to see if the number is divisible by three
Answered by Penny Nom. |
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