Mental Arithmetic: Practice Set 9
This is the ninth timed practice set of 13+ Common Entrance Mental Arithmetic questions on the site, testing the same quick recall and rapid calculation skills as the core Mental Arithmetic topic, the four operations, fractions, percentages, ratio, rounding and simple algebra, worked out rapidly with little or no written working, as in the real timed test.
Before you start
Make sure you're comfortable with these topics first:
Method
- Recall number bonds, times tables and common fraction-decimal-percentage equivalents instantly, rather than deriving them during the test, since Mental Arithmetic is timed far more tightly than a written paper.
- Listen to or read the whole question before starting your calculation, since Mental Arithmetic questions often give numbers in an order different from the order you need to use them.
- Use rounding to estimate an answer quickly and check it against your final calculation, especially under time pressure.
- For questions involving negative numbers, picture a number line and count carefully through zero, rather than guessing the sign of the answer.
- For multi-step word problems, decide on the correct order of calculations before starting, since doing operations in the wrong order is a common cause of mistakes under time pressure.
- Practise little and often against a timer in the weeks before the test, since speed of recall improves with regular short practice more than with occasional long sessions.
Worked example
A number is doubled and then 9 is subtracted, giving a result of 17. Find the original number.
- Form an equation from the description: 2n - 9 = 17.
- Add 9 to both sides: 2n = 26.
- Divide both sides by 2: n = 13.
- State the final answer: the original number is 13.
Practice questions
Type your answer and press Check to be marked straight away, or reveal the answer and mark yourself.
Q1Calculate 74 - 38.Show answer
Answer: 36
Q2Work out 9 x 8.Show answer
Answer: 72
Q3Find 3/5 of 45.Show answer
Answer: 27 (45 / 5 = 9, and 9 x 3 = 27)
Q4Work out 20 - 3 x 4.Show answer
Answer: 8 (multiply first: 3 x 4 = 12, then 20 - 12 = 8)
Q5A recipe uses 2 eggs for every 150 g of flour. Work out how many grams of flour are needed for 5 eggs, at the same ratio.Show answer
Answer: 375 g (150 / 2 = 75 g per egg, and 75 x 5 = 375 g)
Q6Write 0.4 as a fraction in its simplest form.Show answer
Answer: 2/5
Exam-style questions
Written in the style of a 13+ Common Entrance exam paper, with a full mark scheme.
Work out -9 + 4 - (-7).
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 2 available
A charity bake sale raises 96 pounds, shared between two classes in the ratio 5:3. (a) Work out the larger share. (b) The class with the larger share then donates 20% of its share to a second charity. Work out how much is donated.
Show mark scheme
Tick each line you got. Your score builds from the marks on the scheme.
Nothing ticked yet - 4 available
Free printable worksheet
Want more practice on paper? Download the mental arithmetic: practice set 9 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 9 of 13+ Maths Workbook, the whole course as one free printable PDF.
Next topics
Not quite what you needed?
Tell us what is missing on mental arithmetic: practice set 9, or which topic to write up next. Every request is read, and we reply to every one.
Build a full practice pack.
This topic is one of hundreds in the library - pick the ones a student needs and generate a printable PDF in minutes.