statistic & probability
posted by Anonymous .
How many 5 digit numbers can be formed using the digits 0, 1, 2, 3, 4, 5, 6 if repeition are not allowed.
do i use 7P5? since i am choosing 5 numbers from 7 and they can't be repeated?

You have 6 choices for the first digit, which cannot be zero, six for the second digit (which can be zero), five for the third digit, then four and then 3.
That makes 6*6*5*4*3 = 2160 possibilities