11+ fractions, decimals and percentages: compare them easily

To compare or order fractions, decimals, and percentages in an 11+ maths question, convert every value into the same form first — usually percentages or two-digit decimals — before deciding which is largest or smallest. Once the converted values are in order, write your final answer using the original numbers from the question.

In 11+ Mathematics, questions often mix fractions, decimals, and percentages in the same list, table, or word problem to test whether a child understands that all three are different ways of writing parts of a whole. GL Assessment says the school or local authority chooses the subjects and the balance of question types, so check your own test’s guidance.^[1] When a pupil can convert smoothly between the three forms, questions that look awkward at first glance turn into simple whole-number comparisons.

A three-step method

1. Choose one form, usually percentages or decimals

Look at the numbers in the question and pick one target form for all of them:

• Percentages work well when the fractions have denominators that divide neatly into 100 (such as 2, 4, 5, 10, 20, 25, or 50).
• Decimals with the same number of decimal places work well when several decimals are already given (for example, writing 0.7 as 0.70 so you can compare it directly with 0.65 and 0.68).
• A common denominator works best when every number in the question is a fraction whose denominator does not divide cleanly into 100 (such as thirds, sixths, or ninths).

2. Convert each value using known equivalents

Write the converted value directly underneath each original number on rough paper. Knowing the core Key Stage 2 benchmark equivalents makes this step fast and dependable:

• 1/2 = 0.5 = 50%
• 1/4 = 0.25 = 25% and 3/4 = 0.75 = 75%
• 1/5 = 0.2 = 20%, so 2/5 = 40%, 3/5 = 60%, and 4/5 = 80%
• 1/10 = 0.1 = 10% and 1/20 = 0.05 = 5%
• 1/8 = 0.125 = 12.5% and 3/8 = 0.375 = 37.5%

To change any decimal into a percentage, multiply by 100 (for example, 0.65 becomes 65%, and 0.08 becomes 8%).

3. Compare, then give the answer in the form the question uses

Check whether the prompt asks for the largest, the smallest, smallest to largest (ascending), or largest to smallest (descending). Number the converted values in order, then copy the original values (3/5, 0.65, 62%) into the answer box rather than your working percentages.

Common mistakes

• Thinking 0.65 is larger than 0.7 because 65 is larger than 7: Pad decimals with trailing zeros (0.70 versus 0.65) so both numbers show hundredths before comparing.
• Assuming a larger denominator means a larger fraction: A larger denominator splits the whole into smaller pieces, so 1/8 is smaller than 1/5.
• Moving the decimal point the wrong way when changing to a percentage: Remember that 1 = 100%, so 0.06 is 6% (six hundredths), not 60%.
• Answering with the converted value instead of the original: If the question asks which of 3/5, 0.65, or 62% is largest, write 0.65, not 65%.

Practise little and often

1. Spend two minutes a day calling out benchmark fractions (1/4, 3/5, 1/8) and having your child give both the decimal and the percentage.
2. Write three mixed values on paper — one fraction, one decimal, and one percentage — and ask your child to convert all three into percentages underneath before ordering them.
3. Add a quick mental percentage-of-an-amount warm-up by finding 10% and 1% of a number first, then building amounts like 15% or 35%.

Keep practising Mathematics

To try five original 11+ maths questions online with step-by-step explanations, start the free 5-question quiz below.