What factorial equals 720?

1 Answer
Jun 23, 2015

Let's first do it the hard way.

Explanation:

You're trying to find out the solution for
#n! =720#
This means #1*2*3* ...*n=720#

You can divide by all consequtive numbers untill you end up with #1# as a result:
#720//1=720, 720//2=360,360//3=120# etc.

GC (TI-83):
MATH - PRB - !
And try a few numbers.

Answer: 6