Decimal questions test place-value discipline: children who line up the point never lose these marks. Conversions to and from fractions (0.25 = ¼) should be instant recall, and the child who reaches that fluency turns a whole cluster of 11+ questions into near-guaranteed points. This page teaches the skill step by step, shows the traps that quietly cost marks, and points you to the free decimals worksheets and timed mocks on Quest Arena so your child can practise the moment they finish reading.
What 11+ decimals questions actually cover
At 11+ level, decimals is really five connected skills: place value, ordering and comparing, rounding, the four operations, and decimal–fraction–percentage conversion. Under the GL Assessment format that now dominates most regions (CEM's separate paper tests were phased out around 2022–2023), these appear as tightly timed multiple-choice questions — answers marked A to E on a separate OMR sheet, roughly a minute a question, no calculator. Essex CSSE and some independent-school papers ask for written working, so the same skill can appear as free response too. Either way, the underlying method is identical.
- Place value: knowing that in 4.207 the 2 is two tenths, the 0 is zero hundredths and the 7 is seven thousandths.
- Ordering: lining up decimal points and comparing digit by digit — 0.4 is bigger than 0.39, not smaller.
- Rounding: to the nearest whole number, one decimal place or two, using the "5 or more rounds up" rule.
- Four operations: adding, subtracting, multiplying and dividing decimals accurately.
- Conversion: moving fluently between decimals, fractions and percentages.
Place value and ordering: the marks nobody should lose
Most ordering mistakes come from judging by length rather than value. Teach the child to give every number the same number of decimal places by padding with zeros, then compare left to right. To order 0.5, 0.45, 0.405 and 0.5 becomes 0.500, 0.450, 0.405 — now it is obvious that 0.500 is largest. The plain-English version for coaching parents: "a longer decimal is not automatically a bigger decimal." Padding with zeros never changes the value, so 0.5 and 0.50 are the same number.
The four operations, laid out step by step
These are the questions where careful layout beats mental arithmetic. Here is the fully worked method for each.
Adding and subtracting (line up the points): To work out 12.4 + 3.75, write them so the decimal points sit directly under each other, pad 12.4 as 12.40, then add column by column: 12.40 + 3.75 = 16.15. The single rule that prevents nearly every error is keep the decimal points in a vertical line, in the answer too.
Multiplying (ignore the point, then count): For 0.6 × 0.4, ignore the decimals and do 6 × 4 = 24. Now count the decimal places in the question — one in 0.6 and one in 0.4 makes two — so the answer has two decimal places: 0.24. A common wrong answer here is 2.4 (forgetting a place); the count-the-places rule fixes it every time.
Dividing (make the divisor whole): For 4.8 ÷ 0.6, multiply both numbers by 10 so the divisor becomes a whole number: 48 ÷ 6 = 8. Dividing by a decimal feels hard until the child sees it is just balanced scaling.
Rounding without slips
Underline the digit you are rounding to, then look only at the digit immediately to its right. If it is 5 or more, round up; if it is 4 or less, keep the digit the same. Rounding 3.472 to one decimal place: the second decimal digit is 7, so 3.472 becomes 3.5. Rounding 3.472 to two decimal places: the third digit is 2, so it stays 3.47. Encourage the child to say out loud which place they are rounding to — mixing up "one decimal place" and "nearest whole number" is a classic exam trap.
Conversion: the equivalences worth memorising
Fast conversion between decimals, fractions and percentages unlocks marks across the whole maths paper, not just decimals questions. These are worth committing to instant recall:
| Fraction | Decimal | Percentage |
|---|---|---|
| ½ | 0.5 | 50% |
| ¼ | 0.25 | 25% |
| ¾ | 0.75 | 75% |
| ⅕ | 0.2 | 20% |
| 1/10 | 0.1 | 10% |
| 1/3 | 0.333… | 33⅓% |
To turn any fraction into a decimal, divide the top by the bottom (¾ = 3 ÷ 4 = 0.75). To go the other way, write the decimal over its place value and simplify: 0.6 = 6/10 = 3/5. Our fractions and percentages worksheets drill these conversions alongside the decimals sheets so the three topics reinforce each other.
Common exam traps
- Judging by length: thinking 0.125 is bigger than 0.2 because it has more digits.
- Losing the point in multiplication: writing 0.24 as 2.4, or 0.024, by miscounting decimal places.
- Misplaced columns: adding 12.4 + 3.75 as if the 4 and the 7 belong in the same column.
- The last-sentence switch: a worded problem gives a total in pounds and pence, then asks for the answer in pence — always re-read the final question.
- Over-rounding early: rounding partway through a multi-step problem and carrying the error to the final answer.
Difficulty progression: Year 5 to exam-level Year 6
A Year 5 warm-up might be "order 0.3, 0.7 and 0.5" or "what is 0.4 + 0.5?" — single-step, tidy numbers. The exam-level Year 6 version wraps the same skill in a multi-step context: "A ribbon 2.5 m long is cut into pieces of 0.4 m. How much ribbon is left over?" The child must divide (2.5 ÷ 0.4 = 6 pieces, 2.4 m used) then subtract (2.5 − 2.4 = 0.1 m) — two decimals skills and a worded-problem trap in one question. Build from the clean version to the applied one; the free timed mock papers and free papers hub supply the exam-style application.
How to use the worksheets
- Diagnose: one Secure-tier sheet, unaided. Score under 70%? Drop a tier. Over 90%? Climb one.
- Little and often: 15–20 minutes daily beats a weekend marathon — retention lives in the gaps between sessions.
- Review errors out loud: the child explains what went wrong; you resist explaining first. Self-diagnosis sticks.
- Fold into mocks: once a topic hits Greater Depth, let full timed mock papers keep it warm rather than more isolated drilling.
Frequently asked questions
Is a calculator allowed in the 11+ decimals questions?
No. GL Assessment papers are non-calculator, so children must be secure with written column methods and mental shortcuts. That is exactly why lining up the decimal point and counting places by hand matters so much.
How does getting decimals right affect the final score?
Raw marks are converted to a Standard Age Score (roughly 69–141, with 100 as the average and many grammar schools looking for about 111 or above). Because the scaling is age-adjusted, consistent accuracy on high-frequency topics like decimals lifts the score more reliably than occasional flashes of brilliance.
Which year group should start decimals practice?
Place value and simple addition suit Year 4 and 5; multiplication, division and multi-step worded problems are Year 6 exam level but are often tested in the Year 5 autumn assessments, so building the foundation early pays off.