How many 9 digit numbers are possible by using the digits 1,2,3,4,5 which are divisible by 4 if the repetition is allowed?
a)5^7 b)5^6 c)5^9 d)5^8

• ans is 5^8
  ist digit can be 1 or 2,3,4,5. So 5 ways.
  1st 7 digits can have nos(1 or 2,3,4,5).Therefore 5^7 ways.
  last 2 digits can be 12,24,32,44,52. so 5 ways.
  Hence, 5^7*5= 5^8 digits
• 12 years agoHelpfull: Yes(6) No(1)