Question

how many number lie between 11 and 1111 which when divide by 9 leave a remainder of 6 and when divided by 21 leave a remainder of 12

Answer 1

number lies between 11 and 1111 When divide by 9 a remainder of 6 and when divided by 21 leave a remainder of 12 = 33, 96, 159 (all separated by 63)

a =33  d=63

1111=a+(n-1)63
1111=33+(n-1)63
1078=(n-1)63
1078/63=n-1
n=(1078+63)/63
n= 1141/63
n = 18.11
then total number=18

Answer is 18..

I hope its help you.