How many 4 digits number which are greater than 3000 can be formed from 6 digits 123456 if repetitions are not allowed?

The first digit can be any one of four. (3, 4, 5, or 6). For each of these . . .

The second digit can be any of the remaining five. For each of these . . .

The third digit can be any one of the remaining four. For each of these . . .

The fourth digit can be any one of the remaining three.

Total number of possibilities = 4 x 5 x 4 x 3 = 240 .