How many 7 digit numbers can be formed using the digits 1, 2, 0, 2, 4, 2, 4?

There are 7 digits 1, 2, 0, 2, 4, 2, 4 in which 2 occurs 3 times, 4 occurs 2 times.
Number of 7 digit numbers = 7!3! × 2! = 420
But out of these 420 numbers,
there are some numbers which begin with '0' and they are not 7-digit numbers. The number of such numbers beginning with '0'.
= 6!3! × 2! = 60
Hence the required number of 7 digits numbers = 420 - 60 = 360