Question

How many numbers greater than 3000 can be formed the digits 0 1 4 5 8 without repetition of digits?

Answer 1

$3\cdot4\cdot3\cdot2=72$

first digit greater than 3 - (4,5,8 hence 3)

second digit - any of remaining 4 (hence 4)

third digit - any of remaining 3 (hence 3)

fourth digit - any of remaining 2 (hence 2)