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Mathematics · Lesson

Order signed numbers on a number line

Negative numbers look simple until a question mixes fractions, decimals and signs in one list.

On this page
  1. Why do negative numbers feel “backwards”?
  2. How to order a mixed list, step by step
  3. Worked example
  4. The mistake to watch for
  5. Check yourself
  6. Where this leads next

To order signed numbers, place each one on a number line: the further right a number sits, the larger it is. That single rule works for whole numbers, fractions and decimals, with or without a minus sign.

This skill appears early in number sense and exact arithmetic and returns later in inequalities, temperature and bank-balance contexts, and graph work.

Why do negative numbers feel “backwards”?

With positive numbers, a bigger digit means a bigger number: 8 > 3. With negative numbers the sign flips that intuition. −8 means “8 below zero” and −3 means “3 below zero”, so −8 is lower.

Think of a lift in a building with basements. Level −8 is deeper underground than level −3. Going up means moving right on the number line.

How to order a mixed list, step by step

  1. Split the list into negatives, zero and positives. Every negative is smaller than zero, and zero is smaller than every positive.
  2. Convert to one form inside each group, usually decimals, so you compare like with like.
  3. Order the negatives by distance from zero: the one furthest from zero is the smallest.
  4. Order the positives the usual way.
  5. Write the final answer in the order the question asks (ascending means smallest first; descending means largest first).

Worked example

Write these numbers in ascending order: 0.4, −1/2, −0.45, 0, −2, 3/8

Step 1, split: negatives are −1/2, −0.45 and −2. Then 0. Positives are 0.4 and 3/8.

Step 2, convert: −1/2 = −0.5 and 3/8 = 0.375.

Step 3, order the negatives: distances from zero are 2, 0.5 and 0.45. The furthest is −2, then −0.5, then −0.45. So −2 < −0.5 < −0.45.

Step 4, order the positives: 0.375 < 0.4.

Step 5, answer in the original forms:

−2, −1/2, −0.45, 0, 3/8, 0.4

Notice that the final answer keeps the numbers as the question wrote them. Converting was only a tool for comparing.

The mistake to watch for

A common slip is to order negatives by their digits, as if the sign were not there.

Mistaken answer: −0.45, −1/2, −2, 0, 3/8, 0.4

The student saw 0.45 < 0.5 < 2 and kept that order, which ignores the sign.

The correction is to ask “which is further left?” rather than “which digit is smaller?”. Among negatives, the larger the distance from zero, the smaller the number. A quick sketch of the number line with three or four marks is enough to catch this every time.

Check yourself

Try these without a calculator, then open each answer.

1. Put in descending order: −3, 2.5, −3.5, 0.1, −1/4

Show answer

Descending means largest first. Positives: 2.5 > 0.1. Negatives by distance from zero: −1/4 = −0.25 is closest, then −3, then −3.5.

2.5, 0.1, −1/4, −3, −3.5

2. Which is smaller, −2/3 or −0.7? Explain in one sentence.

Show answer

−2/3 ≈ −0.667, and −0.7 is further from zero, so −0.7 is smaller.

3. The temperatures at dawn in four towns were −4 °C, 1 °C, −6 °C and −0.5 °C. Which town was coldest, and which was warmest?

Show answer

Coldest is the smallest value, −6 °C. Warmest is the largest value, 1 °C.

Where this leads next

Once ordering feels automatic, move on to using factors to simplify numerical expressions, then test the whole topic with the number sense practice set. The non-calculator working trainer is useful for building speed without losing accuracy.

Some students understand each step here but still lose marks when signs appear inside longer questions. That is exactly the kind of pattern our teachers look for in online one-to-one Mathematics tuition.

Questions people ask

Is −8 bigger or smaller than −3?

−8 is smaller. On a number line it sits further to the left, and numbers always increase as you move right. The digit 8 is larger than 3, but the negative sign reverses the order, so the number with the larger digits is further below zero.

How do I compare a negative fraction with a negative decimal?

Convert both to the same form first. For example, −3/4 = −0.75, so comparing it with −0.8 becomes a comparison of two decimals. −0.8 is further from zero on the negative side, so −0.8 < −0.75.

Does this topic come up in Core and Extended papers?

Ordering and comparing numbers, including negatives, is foundation number work that supports both routes. Check your own syllabus year on the Cambridge page for the exact wording, because the skill itself stays the same across versions.

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Your next step

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