How many four digit numbers can be made without the first digit being 0 from 2006?
2 choices for the lead digit, now the remaining 3 digits can be arranged in 3!/2! ways
number of ways = 2 x 3!/2!
= 2x3
= 6
Since this is a small number we could actually list them to show why the answer is correct
2006
2060
2600
6002
6020
6200