13+ Common Entrance · Topic guide

Mental Arithmetic: Practice Set 4

Mental Arithmetic: Practice Set 4 is a fourth timed set of 13+ Common Entrance mental arithmetic questions, extending the practice from Sets 1 to 3 with more multi-step word problems across money, measures, fractions and ratio, all worked out without long written calculation.

Year 7-8 (13+)MathsISEB

Before you start

Make sure you're comfortable with these topics first:

Method

  1. Convert all measurements to the same unit before combining them, for example changing metres to centimetres or hours to minutes.
  2. Break a multi-step word problem into separate short calculations, working out and noting each intermediate answer before moving to the next step.
  3. Use known fraction, decimal and percentage equivalents to switch quickly between the three forms, whichever is easiest for the numbers involved.
  4. For money problems, work in pence for intermediate steps to avoid decimal point errors, then convert the final answer back to pounds.
  5. For 'how many left over' or 'how much change' problems, always subtract from the correct starting total, re-reading the question if you are unsure which amount that is.
  6. Double-check a word problem's answer makes sense in context, for example that a length is positive and a number of items is a whole number.

Worked example

A ribbon is 3.6 m long. Pieces of 45 cm are cut from it. Work out how many complete pieces can be cut.

  1. Convert the ribbon's length to centimetres: 3.6 m = 360 cm.
  2. Divide the total length by the length of one piece: 360 / 45 = 8.
  3. So 8 complete pieces of ribbon can be cut.

Practice questions

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Q1Work out 9 x 8.Show answer

Answer: 72

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Q2Find 1/3 of 96.Show answer

Answer: 32

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Q3Convert 2 hours 15 minutes into minutes.Show answer

Answer: 135 minutes

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Q4Work out 40% of 65.Show answer

Answer: 26 (10% = 6.5, so 40% = 26)

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Q5A box of 15 chocolates costs 4.50 pounds. Work out the cost of one chocolate.Show answer

Answer: 30p (4.50 / 15 = 0.30)

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Q6Simplify the ratio 45:30.Show answer

Answer: 3:2 (divide both parts by 15)

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Exam-style questions

Written in the style of a 13+ Common Entrance exam paper, with a full mark scheme.

Q1[2 marks]

Work out 5^2 + 2^3.

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Q2[3 marks]

A parking machine charges 60p for every 20 minutes. Work out the cost of parking for 1 hour 40 minutes.

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Q3[4 marks]

A tank holds 180 litres when full. It is currently 2/5 full. Water is added until the tank is 3/4 full. Work out how many litres of water are added.

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Free printable worksheet

Want more practice on paper? Download the mental arithmetic: practice set 4 worksheet pack - 13 pages of exam-style questions with a full mark scheme. One email opens every download in this browser for 14 days - no account, no card. Print it for personal and classroom use.

This topic is chapter 4 of 13+ Maths Workbook, the whole course as one free printable PDF.

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