Ratios and Proportional Relationships
Percentages
Find a percentage of an amount, and change between fractions and percentages.
Per cent means 'out of a hundred'. So 30% is 30 out of every 100, and if you say 30% of the class walks to school, you mean 30 children out of every hundred do.
The handles worth memorizing
50% is a half, so halve it. 25% is a quarter, so divide by 4. 10% is a tenth, so divide by 10. Almost every percentage question can be built out of those three.
Have a play
This line is the whole of something, split into a hundred. Move along it and read the percentages off.
Tap anywhere on the line.
Worked example
What is 25% of 80?
25% is the same as a quarter.
25 out of 100 simplifies to 1 out of 4.
Try it together
Now let us find 15% of 60.
There is no neat fraction for 15%, so build it out of pieces you already know: 15% is 10% plus 5%.
1.Start with the easy one. What is 10% of 60?
Have a go
Have a go on your own: what is 20% of 150?
Hint: 10% of 150 is 15, and 20% is twice that.
Ready to practice?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.