Question

How many different 4-digit PIN codes are there that only include the digits 4, 5, 7, 8 and 6

if each of those digits is only allowed to be used once?

Answer 1

Available Digits = 4 (1, 2, 3 , 4)

Explanation:

Now, if the digits can be used only once, it is a case of permuting 4 things out of 4 things i.e. 4P4=24ways

Alternatively, the units place can be filled in 4 ways, tens place can be filled in 3 ways, hundreds place can be filled in 2 ways and thousands place in 1 way.

So, TOTAL=4×3×2×1=24

HOPE IT HELPS