Question

find the sum of all two digit number which when divide by 3 yield 1 remaider

Answer 1

ATQ
A.P.=13,16,19,............97
SO, a=13
d=3
An=97
so, An =a+(n-1)d
97=13+(n-1)3
97-13/3=n-1
84/3=n-1
28+1=n
so n=29
Now,...
Sn=n/2{2a+(n-1)d
Sn=29/2(2×13+(29-1)3}
=29/2{26+28×3}
=29/2(26+84)
=29/2(110)
=29×55
=1595ans...