Year 6 Arithmetic (SATs) · Ratio and proportion · Summary
Year 6 Arithmetic (SATs) Ratio and proportion: summary and key words
Part of the Year 6 Arithmetic (SATs) ratio and proportion chapter. Chapter overview · whole chapter on one page
Chapter summary
| Skill | Method |
|---|---|
| Simplify a ratio | Divide both parts by the highest common factor: 12 : 20 = 3 : 5. |
| Ratio and fraction | Add the parts; the first part is a/(a + b) of the whole. |
| Missing value | Find the value of one part, then multiply by the number of parts. |
| Sharing | Add the parts, find one part, then multiply each part by it: 60 in 2 : 3 is 24 and 36. |
| Scale factor | New length ÷ old length; multiply every length by it. |
| Unit method | Find one unit first: £7.50 for 3 packs is £2.50 each, so 5 packs cost £12.50. |
| Percentage of a whole | Part ÷ whole × 100: 90 out of 240 is 37.5%. |
Can you…?
- I can simplify a ratio and write it as a fraction of the total
- I can find a missing value in an equivalent ratio
- I can share an amount in a ratio, including three parts
- I can find a scale factor and use it on a similar shape
- I can use the unit method and write one amount as a percentage of another
Key terms
- ratio
- a comparison of two or more amounts, written a : b
- equivalent ratio
- a ratio with the same relative sizes, such as 2 : 3 and 4 : 6
- scale factor
- the number every length is multiplied by in an enlargement or reduction
- unit method
- a way of working out one unit first, then the amount needed
- similar shapes
- shapes with the same shape but different sizes, with lengths in the same scale factor