FIND THE PROGRESSION

Algebra Level 1

Find the sum of first "n" natural no. and then find the sum of first 100 natural numbers


The answer is 5050.

Aditya Raj by Aditya Raj , 22, India

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3 solutions

Aditya Raj
Apr 13, 2014

The natural no. are 1,2,3.............. these are in A.P with the first term = a=1 and common difference=d=1 the sum to "n" termsof an A.P= n/a[2a+(n-1)d]=n/2(n+1) S100= 100/2*101=5050

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good ques

shishir kumar - 7 years, 2 months ago
Genis Dude
Mar 1, 2017

Let Sum of first 'n' natural numbers be S.

Therefore,

S=1+2+3.....n (eq1)

S=n+(n-1)+(n-2)...+1 (eq2)

Adding eq1 and eq2

2S=n(n+1)

Therefore S=(n(n+1))/2

S100th = (100*101)/2

→5050

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Anukriti Singh
Jun 10, 2014

nothing can be simpler than this !

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