How many 6 - digit numbers can be formed by using the digits 4, 5, 0, 3, 4, 5?
To find: number of 6 digit
0 cannot be in the first place because that would make a 5 - digit number
Total number of 6 - digit numbers = Total number of number possible - Number of numbers with 0 at the first place
Total number of numbers possible = 
Number of numbers with 0 at first place = 
Number of 6 - digit numbers = 180 - 30 = 150
150 six - digit numbers are possible
1