JEE Main2019Math
Q.
The number of function f from {1, 2, 3, ...,20} onto {1, 2, 3, ..., 20} such that f(k) is a multiple of 3, whenever k is a multiple of 4, is :
- A
56 × 15
- B
65 × (15)!
- C
5! × 6!
- D
(15)! × 6!
Solution
