# Reverse Product

Author: mathforces
Problem has been solved: 33 times

Русский язык | English Language

For some positive integer $2020> n> 2$, the fractions $\frac{1}{2}$, $\frac{2}{3}$, $\frac{3}{4}$, ...,$\frac{n-1}{n}$. Find the number of all such $n$ for which some of the fractions can be inverted (that is, replaced by the inverse) so that the product of all fractions becomes equal to one?