Roland's Problem for the Day!!!

It's just as simple as -1+1=0 , because; 1-2=-1 ; -1 x 49 = -49 ... On the other hand, 2-1 = 1 ; 1 x 49 = 49 ... Therefore, 49 + -49 = 0

the answer can found as simple as they said below .

the series is 1-2+3-4+5-6.....................

first 1+3+5+7+9..............

we know the sum first n odd numbers is n^2

so, 1+3+5+7......is the sum of first 25 odd numbers .so the value is 25^2=625

this series appears twice so 625x 2=1250

next series is -2-4-6-8............

the sum of first n even numbers is given by n(n+1).

so,-2-4-6.........is the sum of first 25 even numbers .so the value is 25x26=650(-ve)

it too appears twice ,but 50 only once.so (- 650-625=-650-650+50=-1250)

                               so, +1250-1250=0

                 hence proved the answer is zero

If you look at it carefully, you would notice that the series which gets -ve answers get a +ve answer respectively in the next series. Hence, they are nullified.