QUICK REMINDERS FOR
BASIC SKILLS WITH FRACTIONS, DECIMALS AND
INTEGERS
FRACTIONS
When adding or subtracting fractions, you must have a common
denominator.
2
3
+
3 4
8
=
9
12
17
+ 12 = 12
You do not have to have a common denominator to multiply or divide.
2
x
3
3
6
= 12 REDUCE
4
1
2
When you divide fractions, invert (reciprocal) the second fraction (divisor)
and multiply.
2
÷
3
3
=
4
2
x
3
4
8
=9
3
To multiply or divide mixed numbers, first change them to improper
fractions.
2
2
15 x 23 =
7
5
x
8
3
=
56
15
DECIMALS:
When adding or subtracting decimal numbers, you must line up the decimal
points. If you are adding a whole number to a decimal, add a decimal after the
number and line up the decimal points.
1.2
+ 3.34
4.54
When multiplying decimals, multiply as usual. Make sure there are the same
number of decimal places in the answer as there are in the factors.
1.23 x 2.1 =2. 583
Note: There were two decimal places in the first factor and one decimal place
in the second factor. The answer then has three decimal places.
When dividing by a decimal, move the decimal to the end of the divisor (the
number outside the house). Move the decimal of the dividend (the number
on the inside of the house) the same number of times. Divide as usual.
20.
1.2 24.0.
-24
0
INTEGERS:
ADDITION:
If the signs of the integers are alike, add the numbers and keep the sign.
If the signs of the integers are different, subtract the numbers and keep the
sign of the larger absolute value.
SUBTRACTION:
Change the subtraction symbol to the addition symbol, change the sign of the
next number and follow the rules of addition.
Example 1:
4 - 5 = 4 + -5 = -1
Example 2:
3 – (-4) = 3 + 4 = 7
MULTIPLYING AND DIVIDING:
Multiply or divide as indicated.
If the signs are alike, the result is positive.
If the signs are different, the result is negative.
.