11+ Unit Conversions: Metric Measures and Worked Questions

A ribbon measures 1.8 metres and a second ribbon measures 65 centimetres. Adding the printed numbers gives 66.8, but that number describes no sensible total length. The problem is the units, not the addition. Converting both lengths to the same unit turns a confusing question into ordinary arithmetic.

These original explanations and questions support preparation for 11-plus exams taken in 2027. They are not official school questions or a complete syllabus. Check your target school’s current guidance. Try each question before revealing its answer; written English models illustrate a supported response rather than the only acceptable wording.

Choose a unit before choosing an operation

The physical amount stays the same when its unit changes. Smaller units produce a larger numerical count: 2 metres contains 200 centimetres. Larger units produce a smaller count: 750 grams is 0.75 kilograms. Write the relationship first rather than guessing how many decimal places to move.

Worked example: combine mixed lengths

Convert the first ribbon to centimetres: 1.8 × 100 = 180 cm. Add 65 cm to get 245 cm. If the answer must be in metres, divide by 100: 2.45 m. A quick estimate also helps: a little under 2 m plus a little over half a metre should be roughly 2.5 m.

Worked example: quantities that must be whole

A jug contains 1.65 litres. Each full cup holds 200 ml. Convert first: 1,650 ÷ 200 = 8.25. That means eight full cups, with 50 ml left. It does not mean nine full cups. If the question instead asks how many cups are needed to hold all the liquid, a ninth cup would be partly filled. Read what the final number represents.

Do not transfer a length rule to area

A square metre contains 100 × 100 square centimetres, so 1 m² = 10,000 cm². The length conversion factor is used twice. For this guide’s length, mass and capacity questions, use the table above; for surface measurements, check the square units separately.

Eight questions: keep the units visible

Diagnose the error before repeating the question

If an answer is 100 or 1,000 times too large, inspect the conversion direction. If it is close but not exact, inspect the arithmetic. If a decimal container count was rounded upwards, check whether the question asked for full containers or containers needed. Explain the error in one sentence, then try a changed set of numbers.

What to practise next

Use area and perimeter for square-unit distinctions and fraction, decimal and percentage conversions for numerical equivalence. Return to the maths learning hub or explore original practice and worked answers.

Sources and scope

The Department for Education programme of study provides the curriculum foundation. Our examples, questions and explanations are original. This curriculum reference does not confirm the content, timing or equipment rules of any particular school’s examination.