Find all positive integers $k$, for which the product of some consecutive $k$ positive integers ends with $k$. Proposed by Oleksiy Masalitin
Problem
Source: Ukrainian Mathematical Olympiad 2023. Day 1, Problem 10.1
Tags: number theory, Digits
Source: Ukrainian Mathematical Olympiad 2023. Day 1, Problem 10.1
Tags: number theory, Digits
Find all positive integers $k$, for which the product of some consecutive $k$ positive integers ends with $k$. Proposed by Oleksiy Masalitin