Decimals, Fractions and Percentages
Decimals, Fractions and Percentages are just different ways of showing the same value:
 |
| A Half can be written... |
| |
|
| As a fraction: |
1/2
|
| As a decimal: |
0.5
|
| As a percentage: |
50%
|
|
 |
| A Quarter can be written... |
| |
|
| As a fraction: |
1/4
|
| As a decimal: |
0.25
|
| As a percentage: |
25%
|
|
Example Values
Here is a table of commonly occuring values shown in Percent, Decimal and Fraction form:
|
Percent |
Decimal |
Fraction |
|
1% |
0.01 |
1/100 |
|
5% |
0.05 |
1/20 |
|
10% |
0.1 |
1/10 |
|
12½% |
0.125 |
1/8 |
|
20% |
0.2 |
1/5 |
|
25% |
0.25 |
1/4 |
|
331/3% |
0.333... |
1/3 |
|
50% |
0.5 |
1/2 |
|
75% |
0.75 |
3/4 |
|
80% |
0.8 |
4/5 |
|
90% |
0.9 |
9/10 |
|
99% |
0.99 |
99/100 |
|
100% |
1 |
|
|
125% |
1.25 |
5/4 |
|
150% |
1.5 |
3/2 |
|
200% |
2 |
|
Converting Between Percentage and Decimal
Percentage means "per 100", so 50% means 50 per 100, or simply 50/100. If you divide 50 by 100 you get 0.5 (a decimal number). So:
The easiest way to multiply (or divide) by 100 is to move the decimal point 2 places. So:
| From Decimal |
To Percent |
|
 |
move the decimal point 2 places to the right, and add the "%" sign. |
... or ...
| From Percent |
To Decimal |
|
 |
move the decimal point 2 places to the left, and remove the "%" sign. |
Converting Between Fractions and Decimals
| Steps |
Example |
| First, write down the decimal "over" the number 1 |
0.75 / 1 |
| |
|
| Then multiply top and bottom by 10 for every number after the decimal point (10 for 1 number, 100 for 2 numbers, etc) |
0.75 × 100 / 1 × 100 |
| (This makes it a correctly formed fraction) |
= 75 / 100 |
| |
|
| Then Simplify the fraction |
3 / 4 |
Converting Between Percentages and Fractions
The easiest way to convert a fraction to a percentage is to divide the top number by the bottom number. then multiply the result by 100 (and add the "%" sign)
Example: Convert 3/8 to a percentage
First divide 3 by 8: 3 ÷ 8 = 0.375,
Then multiply by 100: 0.375 x 100 = 37.5
Add the "%" sign: 37.5%
Answer: 3/8 = 37.5%
To convert a percentage to a fraction, first convert to a decimal (divide by 100), then use the steps for converting decimal to fractions.
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