Number Theory
# Divisibility

Is 87985 divisible by 7?

Find the smallest positive multiple of nine containing only even digits.

How many perfect squares have the property that all of their digits are equal?

Note: $0=0^2$ is a perfect square.

$a$ and $b$ are integers, what can we conclude about the expression

Given that$\big( { a }^{ 2 }+a+2011 \big) ( 2b+1 ) ?$

$\frac{(n+2)!}{(n-1)!}$ The above fraction is divisible by which of the following?