The number of permutations of [tex] m(0\leq m\leq n) [/tex] objects from n objects is
[tex] P(m,n)=\frac{n!}{(n-m)!} [/tex]
Here 5 digits are chosen from 6 digits without replacement (order important).
The number of 5 digit numbers that can be formed is
[tex] \frac{6!}{(6-5)!} =6!=720 [/tex]
