How to Add, Subtract, Multiply, & Divide Negative Numbers

By Bon Crowder

Transcript:

How to add, subtract, multiply and divide negative numbers. I'm Bon Crowder with MathFour.com and we're talking about negative numbers and the regular old four operations with negative numbers. So here we have an addition problem, subtraction, multiplication and division all with negative numbers. So let's look at them, -3 + -5 is like saying I borrowed 3 from you today, I borrow $5 from you tomorrow. So how much did I borrow from you total? I borrowed $8 from you because I'm some kind of a bum. This one is not so simple, -2 - -7. We have to remember that in math world two wrongs make a right. So two negatives make a positive. So now we have -2 + 7. So this is like saying I borrowed $2 from you and now I have $7. After I pay you back, I still have $5, -4 x -8, the multiplication and the division are a little squirrelly because there are these seemingly arbitrary rules to them. When you multiply a negative with a negative, because they are matching, you end up with a positive. So -4 x -8 is a positive 32. Likewise, the same negative and negative make a positive rule is -8 divided by -2 makes a positive number. So 8 divided by 2 is 4 and that's a positive four. Notice on the 32 and the 4 you don't actually have to write the positive sign. I'm Bon Crowder with MathFour.com and that's how you deal with negatives.

About the Author

Bon Crowder has taught math to over 15,000 adults in living rooms, classrooms and conferences.