Posted by vincent on Saturday, August 3, 2013 at 3:42pm.
If digits cannot be repeated, how many fourdigit numbers can be made using the digits 1, 3, 5,7, and 9 ?

math  Steve, Saturday, August 3, 2013 at 3:45pm
5*4*3*2 = 120
Each time you choose a digit, the number remaining goes down by one.