Question

Find the sum of all natural numbers from 1 to 200 which are divisible by 5

Answer 1

The sum of all natural numbers from 1 to woo divisible by 5 is as under:
Ist term is(a) 5
Last term is(l) 200
common diffrence(d) is 5
number of terms(n) is 40
Using formula :
sum =n÷2 (2(a)+(n-1)d)
=40÷2 (2 (5)+(40-1)5)
=20 (10+195)
=20 (205)
=4100..