Question

What is the value of 4(-1+2-3+4-5+6-7+......+1000)???

Answer 1

4(-1+2-3+4-5+6-7+......+1000) = 2000

Explanation:

-1+2 = 1

-3+4 = 1

-5+6 = 1

and so on till -999+1000 = 1

1 .... 1000 - these are 1000 numbers, so

1000:2 = 500 pairs with sum equal 1

4(500•1) = 4•500 = 2000