Addition and subtraction
Combine separate counts, remove a part, and find differences or missing parts. Connect objects, equations and number-line moves, then use tens and ones to regroup without changing value.
Key knowledge
For nonnegative integers, addition counts a combined collection when the constituent collections are disjoint. Subtracting b from a gives the number c satisfying c + b = a.
Values and equations
a − b = c ⇔ c + b = a
- a, b, c
- Integers
Conditions and scope
- A whole-number difference exists in the whole numbers only when a ≥ b; integers admit negative differences.
- Counts of overlapping collections require correction for double counting.
Sources · 8
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
National Centre for Excellence in the Teaching of Mathematics2 sources
National Council of Educational Research and Training (NCERT)2 sources
- Ganita Manjari, Grade 9, Part I: §3.3.1: Arithmetic of integersNational 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
Australian Mathematical Sciences Institute and University of Melbourne2 sources
Evidence and review
Sum and inverse subtraction with integer-domain limits.
2026-10-10 · Checked operation meanings and negative-difference qualification.
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
Whole-number addition and subtraction as its inverse.
The repository additionally makes disjointness and overlap correction explicit.
Australian Mathematical Sciences Institute and University of Melbourne2 sources
- TIMES · Addition of whole numbers AustraliaEnglish
Content: combining collections
- TIMES · Subtraction of whole numbers AustraliaEnglish
Motivation; Subtraction is the inverse of addition
- TIMES · Addition of whole numbers
Related articles
Addition and subtraction ↗Entry details
Permanent link to this entry ↗- Record identity
- addition
- Revision
- reference-core.1
- Published lesson seed
- numbers-addition