Question 47152
You are looking for the number of permutations of 4 things (MATH) taken 4 at-a-time.

{{{nPr = (n!)/(n-r)!}}} but in this problem, r = n = 4
{{{4P4 = (4!)/(4-4)!}}} (4-4)! = 0! = 1
{{{4P4 = 4!}}} = 4*3*2*1 = 24