Question

Find the sum of the integers between 100 and 200
that are
(1) divisible by 9. (1) not divisible by 9.
[Hint (in): These numbers will be: Total numbers -
Total numbers divisible by 9)​

Answer 1

refer to attachment:-

Answer 2

between

1)100-200

so, the number which is divisible or multiple of 9 should be written

108,117....198we have

we have a,l,d now ,

now use Sn=[2a+(n-1)d]

         11/2*{108 +198]

        11*153 =1683......................................(1)

An=a+(n-1)d and by

solving we get 11

2)now, not divisible by 9

101,102,103.....199

S99=99/2{102(2)+98(1)

      = now by solving we get

      =14850 .....................................................(2)

hence the sum is subtracting equation 1 &2

=14850-1683

=13167..

that's all the answer is very long procedure.

this can also come in board exams mainly.....

THANK YOU