Daily Math Challenge

Sharpen your math skills with a new problem every Tuesday to Friday. These daily challenges are perfect for those who enjoy quick, engaging puzzles.

Problem 1430

Posted: October 1, 2025

72 % of users got this correct

Find the number of positive integers n such that:

1) n is a multiple of 5
2) 36 < n < 216
3) when expressed in base 6 the rightmost digit of n is strictly greater than it leftmost digit.

This problem is inspired by a problem from the 2011 Harvard - MIT Math Tournament.
Submitted by Mike Schieffer, Austin, TX