JEE Mains Model Paper 4

If first two digits is 41, the remaining 4 digits can be arranged in

8

‌

C4 = 8 × 7 × 6 × 5 = 1680 ways
Similar , If first two digits is 42,46,62,64, the remaining 4 digits can be arranged in

8

‌

C4 way i.e. 1680 ways
∴ Total numbers of telephone numbers having all six digits distinct = 5 x 1680 = 8400