Question

Find the sum of the integers between 100 and 200 that are i) divisible by 9 ii) divisible not by 9...

Please answer my question

Answer 1

Answer:

The nos divisible by 9 = 108 , 117 , 126.....198

the nos are in ap

here a=108 d=9 tn=198 n=?

tn= a+(n-1)d

198=108+(n-1)9

198=108+9n-9

198=99+9n

198-99=9n

99=9n

n=99/9

n=11

sn=n/2(1st term + last term)

s12=11/2(108+198)

= 11/2× 306

= 11×153

=1683