Answer:
here we work with factorials, so if we have a whole number N, then:
N! = N*(N-1)*.....*2*1
then, for the given expressions we have:
1) 6! = 6*5*4*3*2*1 = 720.
2) 3!*21 = (3*2*1)*21 = 216
3) and the last expression seems incomplete, i guess this is:
11! = 11*10*9*8*7*6*5*4*3*2*1 = 39,916,800
