Evaluate. 5!4! = [?]
1 Answer
Mar 28, 2017
2880
Explanation:
What is factorial?
Factorial is the product of an integer and all below it to
#n!# #=n*(n-1)!# for#n≥1# or simply#n!# #=1*2*3*...n#
Notice that
So for
#5!# #=5*(5-1)!# #rArr5!# #=5*4!#
#5!# #=5*4*(4-1)!# #rArr5!# #=5*4*3!#
#5!# #=5*4*3*(3-1)!# #rArr5!# #=5*4*3*2!#
#5!# #=5*4*3*2*(2-1)!# #rArr51# #=5*4*3*2*1!#
But,
Which is
Finally,
#rArr5!# #=5*4*3*2*1#
That is the pattern, so
Or simply;
#rArr120*24=2880#