math
posted by Clint .
How many different 6 digit numbers can be formed using the digits 1,2,3,4,5,6 given that no digit is repeated in a number?

You can put the 1 in any of six locations so 6 so far
then you can put the 2 in any of 5 locations so 6*5 =30 so far
then you can put the 3 in any of 4 locations, so
6*5*4 = 120 so far
etc until
6*5*4*3*2*1 = 6! = 720