Testing divisibility by 7 of number in base 8
30496
Casting nines and elevens in other bases (radix) and doing check sums for binary
38705
Evaluating $\sqrt{1 + \sqrt{2 + \sqrt{4 + \sqrt{8 + \ldots}}}}$
125040
Show by induction : $n^7-n$ is a multiple of 7
98692
How can I test for primality?
145889
Prove if $56x = 65y$ then $x + y$ is divisible by $11$
22973
Show that an integer of the form $8k + 7$ cannot be written as the sum of three squares.
80365
Prove that $n$ is divisible by $6$
99912
Any digit written $6k$ times forms a number divisible by $13$
41641
$(n-7)(n+7)=$ some perfect square
153892
Number Theory divisibilty
27492
Testing if given number is integer
44409
Number of Elements Not divisble by 3 or 5 or 7
10744
Prove that a number is divisible by 3 iff the sum of its digits is divisible by 3
12760
The last 2 digits of $7^{7^{7^7}}$
7473
How am I supposed to tell if a number is divisible by $13$ (I need a shortcut)?
65328
Counts and skips the numbers that have digits divisible by 3 (change in base method)
8318
A positive integer (in decimal notation) is divisible by 11 $ \iff $ ...