# 1.02.03 Methods for dealing with calculations that involve or result in negative numbers.

## 1. Subtracting large positive numbers from smaller positive numbers.

If you subtract a larger positive number from a smaller positive number, it will produce a negative number. The answer you will get will be the same as if you had subtracted the smaller number from the larger one, except that the answer will be negative.

Example.

• 3 - 8 = ?
• (8 - 3 = 5) .
• Therefore 3 - 8 = -5 .

## 2. Subtracting a positive number from a negative number.

If you subtract a positive number from one that is already negative, your result will be a negative number of larger magnitude. (e.g. If you draw out more money from the bank when you are already overdrawn, you will be further in debt!) The answer you will get will be the same as if you added two positive numbers of the same magnitude, except that the answer will be negative.

Example.

• (-3) - 6 = ?
• (3 + 6 = 9) .
• Therefore (-3) - 6 = -9 .

## 3. Adding a smaller positive number to a larger negative number.

If you add a smaller positive number to a larger negative number, you will reduce the magnitude of the negative number. (e.g. If you pay off some, but not all of, your overdraft, you will reduce the amount you owe.) The result can be calculated, by first changing the negative number to a positive number and then subtracting it, then finally changing the answer to negative.

Example.

• (-11) + 6 = ?
• 11 - 6 = 5 .
• Therefore (-11) + 6 = -5 .

## 4. Adding a larger positive number to a smaller negative number.

If you add a larger positive number to a smaller negative number, you will produce a positive number. (e.g. If your account is overdrawn, but you pay in more than you owe, then you will have some money left in your account.) The answer is found as described above, except this time keep the answer positive!

Example.

• (-12) + 16 = ?
• 16 - 12 = 4 .
• Therefore (-12) + 16 = 4 .