Question

Find the sum of the all numbers between 800 and 1100 which are divisible by 79.​

Answer 1

Answer:

869 ,948,1027 are the numbers which is divisible by 79

Explanation:

And other no are 79 *11,79*12, 79*13

Answer 2

first term, a = 869 --------(choose first number divisible by 79 b/w 800 and 1100)

last term,l = 1027---------(choose last number divisible by 79 b/w 800 and 1100)

so the A.P is

869,948...........1027 with common difference, d = 79

now,

l= a+(n-1)d

1027 = 869 +(n-1)79

=>> n-1 = (1027-869)/79

=>> n = 2+1 = 3

so number of terms is 3.

=>> sum of all terms, S = n/2(a+l)

= 3/2(869+1027)

= 2844----------------------ANSWE