(KS2, Year 3)
The LessonA percentage is a part of a whole. It expresses a part of a whole number as parts out of 100. A percentage is shown by the symbol % (said as "percent").
Dictionary DefinitionThe Merriam-Webster dictionary defines a percentage as "a part of a whole expressed in hundredths."
A Real Example of a PercentageA percentage is written as a number followed by the percentage symbol %:
This is 20% (said as "20 percent"). It means 20 parts out of 100.
A Real Example of What a Percentage MeansImagine you were given 20% in a mathematics exam. You would have got 20 out of every 100 marks.
- If there were 100 marks, you would have got 20 marks.
- If there were 200 marks, you would have got 40 marks.
- If there were 50 marks, you would have got 10 marks.
Visualizing PercentagesA percentage shows how many parts out of a 100. A grid with 100 squares is a useful way of visualizing percentages. In the grid below, 20 out of 100 squares are colored blue. 20% of the squares are blue.
Interactive WidgetUse this interactive widget to watch the shapes fill by the percentage specified and the sums complete automatically.
Lesson SlidesThe slider below shows some more examples of visualizing percentages using a grid of 100 squares. Open the slider in a new tab
What's in a Name?"Per cent" comes from the Latin "per centum", meaning "by the hundred". The word "cent" appears in many contexts. In currencies, a hundredth of a US dollar is a cent. A hundredth of a Euro is also a cent. A hundred years is called a century and a hundred year anniversary is a centennial.
Other Types of Fractional NumbersPercentages express a part of a whole. There are other ways of expressing parts of a whole: For example:
- A fraction: 1/2
- A decimal: 0.5
- A negative exponent: 2−1
- A percentage: 50%
- A ratio: 1:2
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