GCSE Maths Notes: Percentages, Decimals and Fractions
Percentages, fractions and decimals are essentially the same idea in different forms. A fraction is one whole number divided by another whole number eg.2 over 5, and so is a percentage, except that the denominator is always 100 eg. 40%=40 over 100. To change any fraction or percentage into a decimal we actually carry out the division, so40%=40 over 100 =0.4.
The table below shows some examples of this equivalence.
|
Fraction |
Decimal |
Percentage,% |
|
2 over 25 |
0.08 |
8 |
|
7 over 50 |
0.14 |
14 |
|
3 over 10 |
0.3=0.30 |
30 |
|
3 over 8 |
0.375 |
37.5 |
|
7 over 20 |
0.35 |
35 |
|
1 over 1 |
1 |
100 |
|
47 over 40 |
1.175 |
117.6 |
|
2=2 over 1 |
2 |
200 |
|
3 over 2 |
1.5 |
150 |
Several things can be noted about the numbers in the table:
A whole number is a fraction since we can write for example, 2 as 2 over 1.
A percentage greater than 100% is possible – the numerator is greater than the denominator.
Given a percentage we can find the fraction by writing the percentage over 100 and the decimal by carrying out the division.
Given a decimal we can find the percentage by writing the multiplying by 100.
Given a fraction we can find the decimal by carrying out the division and the percentage by multiplying by 100.