This website contains problems from math contests. Problems and corresponding tags were obtained from the Art of Problem Solving website.

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Found problems: 52

2013 Saudi Arabia Pre-TST, 2.3
The positive integer $a$ is relatively prime with $10$. Prove that for any positive integer $n$, there exists a power of $a$ whose last $n$ digits are $\underbrace{0...0}_\text{n-1}1$.
last digit power number theory digits

1949-56 Chisinau City MO, 5
Prove that the square of any integer cannot end with two fives.
last digit number theory perfect square digits perfect squares