MEASURES AND TIME

Converting Length

Learn the reliable method for converting length, then apply it to 11+ exam-style questions.

1 · WHAT YOU NEED TO KNOW

The idea

Metric length conversions use fixed place-value relationships.

Picture itConnect the number to its unit and scale
2 · THE METHOD

Follow these steps

  1. Choose one unit for all lengths.
  2. Use 1 km = 1,000 m and 1 m = 100 cm.
  3. Calculate, then convert to the unit requested.
3 · WORKED EXAMPLES

See the method in action

Example 1

What is the difference, in cm, between 6 m and 625 cm?

Conversion bridgeConvert both amounts to cm first6 m625 cm
  1. 6 m = 600 cm.
  2. The difference is 625 − 600 = 25 cm.
Answer: 25 cm
Example 2

A supply contains 10 m. 4 equal portions of 25 cm are used. How much remains in cm?

10 m4 × 25 cm
  1. The used amount is 4 × 25 = 100 cm.
  2. Convert the supply to 1,000 cm, then subtract to get 900 cm.
Answer: 900 cm
4 · ELEVENSPRINT TIP

A useful shortcut

Calculate, then convert to the unit requested.

5 · COMMON MISTAKES

Watch out for these

6 · TRY IT YOURSELF

Three fresh questions

Ready to check the method? You will get three fresh, validated questions.