Here we have to find sum of -1000 and 1000.
The two numbers are equal and opposite in sign.
While adding a positive and a negative , we have to subtract.
so subtracting 1000 -1000, the answer is 0.
Another concept is when we add a number and its negative, we use this property,
a + (-a) =0
For example 2+(-2) = 2-2 =0
Similarly 1000 + (-1000) = 1000-1000 =0
This explains the concept .
