Question

find the sum of all the 2 digit number which when divided by 3 yields 1 as remainder

Answer 1

2 digit no.divisible by 3 are 12,15,18,21........99

so a=12  d=3  an=33

an= a+(n+1)d

ans is =30

follow this method then u will get the answer after that

sn=n/2(a+1)

30/2(12+99)

15*111

1665