This key facts covers Ordering Numbers - The Step-by-Step Method within Place Value & Ordering for GCSE Mathematics. Revise Place Value & Ordering in Number for GCSE Mathematics with 13 exam-style questions and 22 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 5 of 13 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Ordering Numbers - The Step-by-Step Method
For whole numbers:
- Compare the number of digits first (more digits = bigger number)
- If same number of digits, compare from left to right
- Find the first column where digits differ
- The number with the larger digit in that column is bigger
For decimals:
- Compare the whole number parts first
- If whole parts are equal, line up the decimal points
- Add zeros to make all decimals the same length
- Compare digit by digit from left to right after the decimal point
For negative numbers:
- All negative numbers are less than all positive numbers
- For negative numbers: closer to zero = bigger (e.g., -2 > -5)
- Think of a number line: left is smaller, right is bigger
Worked method: ordering decimals, negatives and fractions together
The digit-count trick breaks down once decimals and negatives are involved.
- Pad decimals with zerosLine up the decimal points and add zeros so every number has the same number of decimal places. 0.9 becomes 0.90 and 0.85 stays 0.85. Compare digit by digit — 0.90 has the bigger tenths digit (9 vs 8), so 0.9 is larger, even though 0.85 looks like it has more digits. 'More digits = bigger' only works for whole numbers.
- Order negatives by position, not digit sizeFor negative numbers the bigger the digit, the smaller the value. -7 is smaller than -3 because it sits further left on the number line. Students often assume -7 is bigger because 7 is bigger than 3 — that is the trap. Picture the number line: further left means smaller.
- Convert everything to decimals firstWhen a set mixes fractions, decimals and negatives, convert every value to a decimal before comparing. 3/4 becomes 0.75, 1/2 becomes 0.5. You cannot compare a fraction to a decimal directly.
- Build one number lineOnce everything is a decimal, order left to right: most negative first, then closer to zero, then zero, then positives smallest to largest. Negatives always come before positives however large the negative digits look.
- Check ascending or descending before answeringAscending is smallest to largest; descending is largest to smallest. Re-read the question — a perfectly ordered list written in the wrong direction still loses the marks.
- Pair-check your final orderBefore finishing, check each neighbouring pair with an inequality sign. If every pair matches the direction the question asked for, the answer is solid.
Write these numbers in order, starting with the smallest: -3, 0.6, -1.5, 3/4, -2
Convert 3/4 to a decimal: 3/4 = 0.75. Every number is now a decimal: -3, 0.6, -1.5, 0.75, -2. Order the negatives from most negative to least: -3, -2, -1.5. Then the positives smallest to largest: 0.6, 0.75. Smallest to largest: -3, -2, -1.5, 0.6, 3/4.
The most commonly lost mark is ordering the negatives backwards — writing -1.5 before -2 before -3, treating bigger digits as bigger values. Check negatives by position on the number line, not digit size.
Practice questions for Place Value & Ordering
What is the value of the digit 7 in the number 47,362?
Write these numbers in order from smallest to largest: -3.2, 0.8, -1.5, -3.25, 0