To find: number of 7 digit
0 cannot 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 = \(\frac{7!}{3!2!}\) = 420
Number of numbers with 0 at first place = \(\frac{6!}{3!2!}\) = 60
⇒ Number of 7 - digit numbers = 420 - 60 = 360
360 seven - digit numbers are possible