Question

The total number of numbers less than 100 and divisible by 5 formed with 0,1,2,.....9 such that each digit doesn't occur more than once in each number is
HINT:154
Answer if you know
PLS DON'T SPAM​

Answer 1

unit digit : 0 or 5..

if unit digit = 0

2-digit no = 9x1 = 9

3-digit no = 9x8x1 = 72

if unit digit = 5

1-digit no = 1

2-digit no = 8x1 = 8

3-digit no = 8x9x1 = 72 (including 0 at 100's place)

actual 3-digit no = 72 - 8 = 64

total no = 1 + (9+8) + (72+64) = 154.... ans