What formula is used for this problem?
Evaluate
20!
18!
The "!" denotes the factorial of the number preceeding it. It is the product of
all the integers less than the number and greater than 1. By convention we take 0!=1.
So:
20!= 1x2x3x4x5...x18x19x20
18!= 1x2x3x4x5...x18.
So:
20!/18!=(1x2x3x4x5...x18x19x20)/(1x2x3x4x5...x18)=19x20=380
RonL