31x5 divisible by 3 ?
∵ 31x5 is divisible by 3⇒ 3+1+x+5 is a multiple of 3⇒ 9+x=0,3,6,9,....⇒ x=−9,−6,−3,0,3,6,9,....Since, x is a digit∴ x=0,3,6 or 9
Question 31 A number is divisible by 5 and 6. It may not be divisible by (A) 10 (B) 15 (C) 30 (D) 60
Show that:
(i) 133−53 is divisible by 8.
(ii) 353+273 is divisible by 62.