Question

Find sum to n terms from the following series 52,51,50 and so on till 25 term

Answer 1

Sum till n terms = n*(n+1) / 2

So sum up to 52 = 52 * (52+1) / 2 = 1378 ------(1)

we need sum up to 25 terms so 52 - 25 = 27

Sum up to 27 = 27 * (27+1) / 2 = 27 * 28 / 2 = 27 * 14 = 378 ------(2)

Subtracting (2) from (1) = 1378 - 378 = 1000 is the sum of 52,51,50 series upto 25 digits