Question 112
$1 \cdot 2 \cdot 3 \cdot \dots \cdot n$
is written on a blackboard. For which positive integers $n \ge 2$ can we append the exclamation mark to some factors and change them to factorials in such a way that the final product will be a square?
is written on a blackboard. For which positive integers $n \ge 2$ can we append the exclamation mark to some factors and change them to factorials in such a way that the final product will be a square?