Mahabharata 3

The answer is $\dfrac{99 × 100}{2} = \color{#69047E}{\boxed{4950}}$ .

Sum of 'n' terms in A.P. is given by = n/2[A+L], where A=1st term & B= 2nd term

= (1+2+3+4+5+ ... + 100) - 100 = 5050 - 100 = 4950

sum of natural number= (n*(n+1))/2, where n is the last number.

1 + 2 +3 + .............................. + 99

99 + 98 + 97 .......................... +1

adding both

100 + 100 +100 ..............................(99 times)

therefore $\frac{100X99}{2}$ = 4950

this solution was done by a 10 year old boy

its an interesting story

Its nearly about 150 years back, in a village a teacher taught addition,the next day he wanted to relax,so he gave that add

1 +2 +3 ..........................+ 100

everyone started adding 1 +2 then 3 +3 ......................

After few minutes a boy started looking outside, the teacher went to him and saw his notebook , he was astonished to see the above. at the end of the period the students who counted got wrong results and the boy got right result as well as in few seconds

and today we now the formula for sum of first n natural numbers that is $\frac{n(n +1)}{2}$

this above result is derived from this 10 year old boy method

the boy name was---------------

CARL FRIEDRICH GAUSS ( the great mathematician )

Think different

s=n/2(a+l)=99/2(1+99)=4950