This presentation reviews math skills for everyday problems, including operations on integers. It discusses rules for adding, subtracting, multiplying and dividing integers. When adding or subtracting integers, the sign of the answer depends on the signs of the numbers. For multiplication and division, the answer is positive if an even number of factors are negative, and negative if an odd number are negative. Examples are provided to demonstrate applying the rules.

1. This presentation will review different math skills that will help you
with every day math problems.
Operations on Integers

2. Use these hints to help work problems.
If both numbers are negative, add the numbers, then make the answer
negative.
-8 – 2  -(8 + 2) = -10
When one sign is positive and one sign is negative, subtract the
numbers and take the sign of the larger.
8 – 2 = 6 (“8” is positive, so the answer is positive)
2 – 8 = -6 (think “8-2” and take the sign of the larger number, “8”)
Examples:
++  9 + 2 = 11
--  -9 – 2 = -11
+-  9 – 2 = 7
-+  -9 + 2 = -7
Addition & Subtraction
Try using this chart:
Integer Addition/Subtraction
++  Add
--  Add
+-  Subtract
-+  Subtract
Always use the sign of the largest
number for the sign of the answer

3. Try it yourself
3 + 6 = 9 -3 – 6 = -9 3 – 6 = -3 -3 + 6 = 3
4 + 7 = -4 – 7 = 4 – 7 = -4 + 7 =
7 + 4 = -7 – 4 = 7 – 4 = -7 + 4 =
5 + 1 = -5 – 1 = 5 – 1 = -5 + 1 =
10 + 20 = -10 – 20 = 10 – 20 = -10 + 20 =
4 + 7 = 11 -4 – 7 = -11 4 – 7 = -3 -4 + 7 = 3
7 + 4 = 11 -7 – 4 = -11 7 – 4 = 3 -7 + 4 = -3
5 + 1 = 6 -5 – 1 = -6 5 – 1 = 4 -5 + 1 = -4
10 + 20 = 30 -10 – 20 = -30 10 – 20 = -10 -10 + 20 = 10
Addition & Subtraction
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4. If there are 2 signs next to each other, rewrite the
problem with just one sign.
To subtract a negative number, the 2 negatives make a positive.
8 – (-2)  8 - -2  8 + 2 = 10
Adding a negative number is the same as subtraction.
8 + (-2)  8 + -2  8 – 2 = 6
We don’t usually write the
positive sign, but you could if you
wanted to:
8 + 2  (+8) + (+2)
8 – 2  (+8) – (+2) or (+8) + (-2)
The parentheses are only
there to keep the signs
separate. You can remove
them if you want to.
Addition & Subtraction of Integers

5. Try it yourself
3 – (+6)  3 – 6 = -3 -2 – (-4)  -2 + 4 = 2
4 – (-2) = -8 + (-3) =
-10 + (-3) = 10 – (+2) =
9 + (+2) = -7 – (-3) =
4 – (-2) = 6 -8 + (-3) = -11
-10 + (-3) = 7 10 – (+2) = 8
9 + (+2) = 11 -7 – (-3) = -4
Addition & Subtraction
End of Lesson 12
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7. Multiplication & Division of
Integers

8. Some simple rules will help you when multiplying negative numbers. The
rules are the same for division.
 If there is one negative number, then the answer is negative.
 If two numbers are negative, then the answer is positive.
8 x 5 = 40 40 ÷ 8 = 5
-8 x 5 = -40 -40 ÷ -8 = 5
8 x -5 = -40 -40 ÷ 8 = -5
-8 x -5 = 40 40 ÷ -8 = -5
 If you have more than 2 numbers, the rule is:
 An odd number of negative #s = negative answer
 An even number of negative #s = positive answer
(-1 )x (-2) x (-3) x (4) = -24 (3 negative #s)
(-1) x (-2) x (-3) x (-4) = 24 (4 negative #s)
Multiplication and Division of Integers
If the signs are the same = positive answer.
If the signs are different = negative answer.
Integer Mult./Division
++  Answer is +
--  Answer is +
+-  Answer is -
-+  Answer is -

9. Try it yourself
2 x 3 = 6 -2 x 3 = -6 2 x -3 = -6 -2 x -3 = 6
6 x 8 = - 6 x 8 = 6 x -8 = -6 x -8 =
7 x 4 = -7 x 4 = 7 x -4 = -7 x -4 =
54  6 = -54  6 = 54  -6 = -54  -6 =
|-8 x 3| = |5 x (-2) – 1| = 2 x |3 – 9| = |-12  -4| =
6 x 8 = 48 - 6 x 8 = -48 6 x -8 = -48 -6 x -8 = 48
7 x 4 = 28 -7 x 4 = -28 7 x -4 = -28 -7 x -4 = 28
54  6 = 9 -54  6 = -9 54  -6 = -9 -54  -6 = 9
|-8 x 3| = 24 |5 x (-2) – 1| = 11 2 x |3 – 9| = 12 |-12  -4| = 3
15 Minute Math – Integers
Lesson # 13 – Multiplication, Division, &
Absolute Value
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