Suppose that $A$ is an $n \times n$ matrix with integer entries and $\det A = p_1^{e_1} p_2^{e_2} \dots p_k^{e_k}$ for primes $p_1, p_2, \dots, p_k$ and positive integers $e_1, e_2, \dots, e_k$. Prove that there exist $n \times n$ matrices $B_1, B_2, \dots, B_k$ with integer entries such that $A = B_1 B_2 \dots B_k$ and $\det B_1 = p_1^{e_1}, \det B_2 = p_2^{e_2}, \dots, \det B_k = p_k^{e_k}$.

The best solution was submitted by Lee, Sangmin (이상민, 수리과학과 2014학번). Congratulations!

Here is his solution of problem 2016-10.

Alternative solutions were submitted by 국윤범 (수리과학과 2015학번, +3), 장기정 (수리과학과 2014학번, +2), 박정우 (한국과학영재학교 2016학번, +2).