How can you find the sum of any two negative numbers

The sum of any integer and its opposite is equal to zero. Adding two positive integers always yields a positive sum, adding two negative integers always yields a negative sum. To find the sum of a positive and a negative integer, take the absolute value of each integer and then subtract these values.

If you can use a calculator that would be easiest but a negative plus a negative equals a negative number - 1+-1=-2