How many 7 - digit numbers can be formed by using the digits 1, 2, 0, 2, 4, 2, 4?
To find: number of 7 digit
0 can not be in the first place because that would make a 6 digit number
Total number of 7 - 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 7 - digit numbers = 420 - 60 = 360
360 seven - digit numbers are possible
1