Question

How many 5 digit numbers formed using the digits 0,1,2,3,4,5 are divisiable by 3 if digits are not repeted

Answer 1

Answer:

s={10, 12,13,14,15,20,21,23,24,25,30,31,32,34,35,40,41,42,43,45,50,51,52,53,54}

n(s) =25

Event A : numbers divisible by 3

A={12, 15,21,24,30,42,45,51,54}

n(a) = 9