We can also use the rules to solve this. The signs of the numbers are different, so we subtract the numerals and keep the sign of the larger number. 21 – 5 is 16 and since 21 is the larger number and is positive, the answer is positive 16.
Example 2
What is (-4) + (-8)?
There are 4 negatives and 8 more negatives, making 12 negatives, or -12.
We can use the rules to solve this as well. The signs of the two numbers are the same: they're both negative. So we add the numerals 4 and 8 and keep the negative sign, making -12. Didn't even break a sweat.
Example 3
What is (-50) + 20 + (-10) + 55?
Working with four numbers isn't all that different from working with two numbers. We start with the first two numbers:
(-50) + 20 = -30
The signs are opposite, so we subtract and keep the sign of the larger number.
Now, we add -30 to the next number:
(-30) + (-10) = -40
Here the signs are the same, so we add the numerals and keep the sign.
Finally, add (-40) to the last number, 55.
(-40) + 55 = 15
Because the signs are different, we subtract and keep the sign of the larger numeral. And that's our answer!
Example 4
What is (-14) + (-21) + 35?
The sum of these first two Negative Nancies is -14 + (-21) = -35.