n!/(n-2)!=n(n-1)=930
Second degree equation
You can simplify by (n-1)(n-2) considering that 1 and 2 are not solutions of initial equation
(n-3)(n-4)=42
You can solve by using usual method of second degree equation or just looking at the equation
n-3 and n-4 are two consecutive integers
You surely know two consecutive integers whose product gives 42
One is equal to n-3 and the other one to n-4