4
Problems(2)
4 cars in a rally on a circular racecourse (2021 Auckland MO J4)
Source:
11/14/2021
Four cars participate in a rally on a circular racecourse. They start simultaneously from the same point and go with a constant (but different) speeds. It is known that any three of them meet at some point. Prove that all four of them will meet again at some point.
algebra
2021 / 7^m - 7^n (2021 Auckland MO S4)
Source:
11/15/2021
Prove that there exist two powers of whose difference is divisible by .
number theorypowersdividesdivisible