Integers

Integers

Integers - are a set of positives or negatives and their opposites (negatives or positives).

ex. 4 is a positive number. The opposite of positive 4 is negative 4 (-4). -5 opposite 5

note: 4 is bigger than -4.



Addition Rules

1. If the signs are the same (-3 + -4), then add the numbers and keep the sign of the numbers. -3 + -4 = -7 2 + 6 = 8 -5 + -9 = -14


2. If the signs are different ( -2 + 5), than subtract the small actual number (2) from the bigger actual number (5). Keep the sign of the bigger number (5). -2 + 5 = 3 -14 + 7 = -7

Subtraction Rule

1. Change the subtraction symbol to a plus then change the second number to it's opposite. -3 - 7 = -3 + -7 = -10 12 - 5 = 12 + -5 = 7 18 - -9 = 18 + +9 = 27


2. The two pencil mark rule - when you have an integer minus a negative you do two marks. You change the minus to a plus, then the negative sign to a plus. 17 - -8 = 17 + +8 = 25 -6 - -9 = -6 + +9 = 3

Subtraction really doesn't exsist! Any regular subtraction problem is really a number plus a negative.

Multiplication and Division

You think of multiplication as repeated addition.

1. 3 x 2 = 2 + 2 + 2 = 6 then 3 x -2 = -2 + -2 + -2 = -6


2. When the signs are the same ( 4 x 5 or -9 x -3), the answer is a positive ( 4 x 5 = 20 and -9 x -3 = 27).


3. When the signs are different ( 6 x -4 or -2 x 8), the answer is a negative ( 6 x -4 = -24 and -2 x 8 = -16).

It's the same rules for division.

Here's two sights that will help you learn, or if you just want to learn more: http://www.mathleague.com/help/integers/integers.htm http://www.math.com/school/subject1/lessons/S1U1L10GL.html

Here's something for practice: http://www.math-drills.com/integers.shtml