Fractions & percentages
Percentages
Percent and percentage mean the number of parts out of a hundred. The symbol is %. You see percentages on sale signs and food labels every day.
Percent means out of 100
A percentage tells you how many parts there are out of 100. The symbol % means percent. If a diagram has 100 squares and 25 of them are shaded, that is 25 out of 100, which is 25%. 100% represents the whole.
Simple percentages as fractions
Some percentages match fractions you already know: ā¢ 50% = 1/2 ā¢ 25% = 1/4 ā¢ 75% = 3/4 ā¢ 10% = 1/10 ā¢ 20% = 1/5 You can also go the other way: 3/10 is the same as 30 out of 100, which is 30%.
Percentages that make a whole
Because the whole is 100%, all the parts add up to 100%. If a dress label shows 50% cotton and 25% wool, the missing part is 100 ā 50 ā 25 = 25%. If 55% of a class are boys, then 100 ā 55 = 45% are girls.
Worked examples
Read a percentage from a grid
- The grid has 100 small squares.
- Count the shaded squares: 25.
- 25 out of 100 is written as a percentage.
Answer: 25% is shaded.
Change 3/10 to a percentage
- Make the bottom number 100: 10 Ć 10 = 100.
- Do the same to the top: 3 Ć 10 = 30.
- So 3/10 = 30/100.
Answer: 3/10 = 30%.
Find the missing percentage
- The whole is 100%.
- A dress is 50% cotton and 25% wool.
- 100 ā 50 ā 25 = 25.
Answer: 25% of the dress is silk.
Where you see this in real life
- Reading 'SAVE UP TO 50%' on a sale sign.
- Seeing that a burger gives 11% of the energy an adult needs.
- Working out that if 55% of a class are boys, 45% are girls.
- Understanding a battery that shows 80% charged.
Key words
- Percent
- The number of parts out of a hundred.
- Percentage
- Another word for percent, the number of parts out of 100.
- % (percent sign)
- The symbol that means 'out of 100'.
- Whole
- All of something, which is 100%.