Adding positive numbers....just add as usual,,,,the answer, of course, will be positive
Adding negative numbers....forget the signs......add as you would two positives......go back and append a "negative" sign to the answer....Example -21 + (- 13 ) = -21 - 13.....Add 21 + 13 = 34 .....append the negative sign to the result = -34
Numbers with different signs.....this usually causes the most trouble.......here's the "trick' :
Forget the signs.......take the "smaller" number and subtract it from the "larger"......in the answer, use the sign that was on the "larger" number
Ex :
-21 + 6
Forget the signs
Take the "larger" number, 21, and subtract the "smaller" number
21 - 6 = 15
Now.....use the sign that was originally on the "larger" number.....this is a negative......so....the aswer is : - 15
One more note....subtracting a negative turns it into a positive
Ex :
-15 - (-9) = -15 + 9 and now.....we just use the last rule
15 - 9 = 6 ....and since the "larger" number was negative......the answer is - 6
Hope that helps......
