Number lines and order
Use number-line positions to compare whole numbers. Read the scale, recognise equality, and distinguish numerical distance from drawing size.
Key knowledge
After choosing an origin, positive direction and unit length, real numbers are represented by points on a line. With values increasing to the right, a < b places a to the left of b; their numerical distance is |b − a|.
Values and equations
d(a,b) = |b − a|
- a, b
- Real coordinates in the same unit
- d(a,b)
- Nonnegative numerical distance
Conditions and scope
- Equal numerical differences use equal distances on a linear scale.
- The expression gives numerical distance in the chosen unit.
Sources · 7
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
- Drawing and Reading Number LinesAustralian Association of Mathematics TeachersTeaching resource
National Council of Educational Research and Training (NCERT)2 sources
- Ganita Manjari, Grade 9, Part I: §3.4.1: Rational numbers on the number lineNational Council of Educational Research and Training (NCERT), IndiaTextbook chapter · PDF
- Ganita Manjari, Grade 9, Part I, chapter 3: Number systems (2026–27)National Council of Educational Research and Training, IndiaTextbook chapter · PDF
- TIMES · Real numbersAMSI and University of Melbourne, ICE-EMTeaching resource
Evidence and review
Orientation, equal intervals and absolute-value distance.
2026-10-10 · Compared NCERT's rational-number representation with the real-number distance used in calculus.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Scope or convention differs
Real numbers as ordered points on a line with a chosen unit.
The geometric construction supports the linear scale; the general absolute-distance formula is additional precision.
Australian Mathematical Sciences Institute and University of Melbourne
- TIMES · Real numbers AustraliaEnglish
Real numbers; Arithmetic and geometry
- TIMES · Real numbers
Related articles
Number lines, order and comparison ↗Entry details
Permanent link to this entry ↗- Record identity
- number-lines
- Revision
- reference-core.1
- Published lesson seed
- numbers-number-line