Percentage: per hundred
You learn what a percentage is: the whole strip is 100%, and you also write percentages as fractions and decimals.
How to work it out
- See percentage as "out of a hundred": the whole strip is 100%.
- When you divide the strip into pieces, you also divide that 100.
- From fraction to percentage: divide 100 by the denominator and times by the numerator.
- From percentage to decimal: move the decimal point 2 places to the left.
- From decimal to percentage: move it 2 places to the right.
310
A worked example
34 = ? %
- The whole strip is 100%.
- Divide 100 by 4: one piece is 25%.
- Multiply by 3: 3 × 25 = 75.
- It is 75%.
34
More examples
25% = ? as a decimal
- Divide 25 by 100.
- Move the decimal point 2 places to the left: 25 becomes 0.25.
5% = ? as a decimal
- Divide 5 by 100.
- Move the decimal point 2 places to the left and fill in a 0: 5 becomes 0.05.
0.6 = ?%
- Do 0.6 times 100.
- Move the decimal point 2 places to the right: 0.6 becomes 60.
- It is 60%.
Try it yourself
25% = ? as a decimal
0.15 = ?%
Watch out
You write the fraction as a percentage: 34 becomes 34%.
A fraction is not a number with two digits. Work it out using the 100.
You write 5% as 0.5.
0.5 is 50%. At 5% there is a 0 in between: 0.05.
Tips
- A half is 50%, a quarter is 25% and a tenth is 10%.
- From decimal to percentage the decimal point goes right, because percentage is a bigger number.
Why it works
Percentage means "out of a hundred": the whole strip is 100%. When you divide the strip into pieces, you also divide that 100, and that way you know how many percent one piece is. 25% is 25 out of 100, and that is 0.25. Dividing by 100 moves the decimal point two places to the left, times 100 moves it back.