Game with divisors, gcd and lcm
Source: Kvant Magazine No. 2 2023 M2737
April 19, 2023
number theorycombinatorics
Problem Statement
All the divisors of a) and b) are written on a board. At a move, we can take two numbers, neither of which is divisible by the other, and replace them with their greatest common divisor and lowest common multiple. At some point, we will no longer be able to perform new operations. How many different numbers will be on the board at this moment?Proposed by V. Bragin