Maths: Measures

In a measures question, you get a short story with amounts in it, in two different units, like litres and millilitres.

Your job is to work out the answer in the unit the question wants, and pick it from five answers. In GL's papers the five answers carry their units, so read the unit as well as the number. The video above and the worked example below work through the same question, with the options in the same order.

The method

Four steps: spot the units, make them the same, do the step, answer in the unit asked.

Worked example

A bottle holds 3 litres of water. Oliver pours out 725 ml. How much water is left in the bottle?

A. 2,265 ml B. 2,275 ml C. 3,725 ml D. 29,275 ml E. 2,275 l

1. Spot the units. Here, the bottle holds litres, but the water poured out is in millilitres. The question doesn't name a unit, so look at the answers. Four of the five are in millilitres, so the answer needs millilitres.
2. Make them the same. Change the amounts into one unit before you work. 1 litre is 1,000 millilitres, so 3 litres is 3,000 millilitres. Now both amounts are in millilitres. Option D, 29,275, starts from 30,000 millilitres, as if a litre were 10,000. A litre is only 1,000, so D is out.
3. Do the step. With everything in millilitres, do the one sum the story needs. Water is poured out, so take it away: 3,000 − 725 = 2,275 millilitres. Two options are slips in the take-away. 2,265 is option A. It's ten short, because the tens were exchanged twice, so A is out. 3,725 is option C. In every column, the smaller number was taken from the bigger one. That's more than the bottle held at the start, so C is out.
4. Answer in the unit asked. Check your answer is in the unit the answer needs. We need millilitres, and 2,275 ml is there. Option E has the same number, but in litres. That's far more than a 3-litre bottle, so E is out. So the answer is B.

Answer: B — 2,275 ml (3 l = 3,000 ml, and 3,000 − 725 = 2,275 ml)

Things to watch out for

1. Count the zeros. A litre is 1,000 millilitres, and a kilogram is 1,000 grams, but a metre is only 100 centimetres. In the worked example, D took 10,000 millilitres for each litre.
2. Answer in the unit it asks for. The right number in the wrong unit can be one of the answers. In the worked example, E was 2,275 litres: the right number, but in litres, not millilitres.
3. Use every piece of the story. A jug holds 3 litres of lemonade, and Felix pours 3 glasses of 150 ml each. Three glasses make 450 ml. 2,850 ml takes off only one glass. 3,000 − 450 leaves 2,550 ml.
4. On a scale, count the gaps. Count the gaps, not the marks. Here, a jug's scale is numbered every 100 ml, up to 500 ml. Each 100 ml is split into five gaps by four small marks, so each gap is 20 ml. The water is three gaps past 300: 360 ml. 300 ml is only the number below, and 330 ml counts each gap as ten.

Related

• The complete 11+ question-type guide
• Maths: Place Value and Ordering — every gap is a zero, so check the zeros
• Maths: Percentages — same units first: pence with pence, pounds with pounds
• Maths: Word Problems — plan, then finish every step

All example questions come from the Brainblox question bank — practise this question type inside 25+ learning games, timed mock exams and focused practice. Brainblox is an independent app: not affiliated with, endorsed by or licensed by any exam board, school or assessment publisher, and it contains no past papers.