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Subtraction of Integers:

Subtracting a number yields the same result as adding the inverse of a number . Notice I added the parenthesis. These parenthesis do nothing to the problem. You can leave them in or take them out. So, to subtract two numbers we don't need to memorize another set of rules. All we have to do is:

	Convert the difference to sum. Other words: Change the minus sign to plus sign.
	Change the sign of the number after the minus sign. Use the rules of addition.

Example:
Subtract:

Question	Rewrite	Answer	Reason
4 - 6 =	4 + -6 =	-2	(6 - 4 = 2) Keep the sign of the larger.
7 - 3 =	7 + -3 =	4	(7 - 3 = 4) Keep the sign of the larger.
8 - -5 =	8 + 5 =	13	2 minus signs = positive sign
5 - 9 =	5 + -9 =	-4	(9 - 5 = 4) Keep the sign of the larger.

Example:

eq101795.gif (4135 bytes)

Change - sign to + sign and switch the sign of the following number.

Example:

eq101796.gif (5686 bytes)

Change - sign to + sign and switch the sign of the following number.

Example:

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Example:

eq101798.gif (1521 bytes)

Notice: 2 minus signs will make a positive sign.