







4821x14y is an 8digit number divisible by 72 
20140806 

RAYA pose la question : if 4821x14y is an 8digit number divisible by 72. How many values can x and y take? Penny Nom lui répond. 





A 4 digit number 
20140404 

LIM pose la question : "A" is a 4 digit number formed by all the numbers from 1 to 4. When "A" is divided by 9, the remainder is the biggest possible value. What is the biggest value of A? Chris Fisher lui répond. 





An even multiple of 27 
20110201 

parth pose la question : the 6 digit # 63x904 is an even multiple of 27 what is X Penny Nom lui répond. 





Powers 
20101020 

dylan pose la question : 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. Penny Nom lui répond. 





Divisibility rules 
20010907 

A student pose la question : 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. Penny Nom lui répond. 





Divisibility by 9 
20001024 

Kelera pose la question : If the sum of the digits of a number is divisible by 9, then the number itself it divisible by 9. Why is that? How do you explain this? Penny Nom lui répond. 





Divisibility by 3 
20000324 

Pat Walsh pose la question : 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 Penny Nom lui répond. 





Divisibility by 9 
19990221 

Razzi pose la question : I've been having a hard time trying to solve the following problem and I was wondering if you could help me. For any positive integer a let S(a) be the sum of its digits. Prove that a is divisible by 9 if and only if there exist a positive integer b such that S(a)=S(b)=S(a+b). Chris Fisher and Harley Weston lui répond. 

