Question

1-2+3-4+5-6+7-8+......+19-20

Answer 1

-10...is the answer......

hope that helps u ....

Answer 2

Answer : -10,

Here is the solution :

Divide The whole set into 2-2 parts,

That is,

(1-2) + (3-4) + (4-5) +.........+(19-20),

Now, Each set contains 2 numbers, with -ve sign,

Also, Each set value is -1,

1-2 = -1
3-4 = -1
5-6 = -1................
19-20 = -1,

The total numbers were 20, When we've divided it into sets of 2,

We have 10 sets with each value of -1,

So 10*-1 = -10,

Therefore : The answer is -10,

Hope you understand, If you have Doubts Comment,

Thanking you,
Bunti 360 !..