Real-number arithmetic laws
Real arithmetic permits regrouping, distributing and taking nonzero reciprocals.
Key knowledge
Real addition and multiplication commute and associate; multiplication distributes over addition. Zero and one are their identities. Every real number has an additive inverse; every nonzero real number has a reciprocal. Subtraction adds the opposite.
Values and equations
a+b=b+a; ab=ba; (a+b)+c=a+(b+c); (ab)c=a(bc); a(b+c)=ab+ac; a+0=a; a·1=a; a+(−a)=0; a/a=1 (a≠0); a−b=a+(−b)
- a, b, c
- Real numbers
Conditions and scope
- Use ordinary real numbers. Division by zero is undefined.
- These exact laws do not guarantee identical results after finite machine rounding.
Ordinary real arithmetic only; no machine arithmetic guarantee.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Checked the stated real-number arithmetic laws and restrictions against the listed primary sections; exact inspected boundaries are in the author receipt.
2026-10-10 · Independent Physics and Measurement reference editor (AI editorial bounded review). Independent AI editorial review of this entry's statements, equations, applicability conditions and source coverage. Source checks apply to these claims within their stated limits.
Entry details
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- foundation-math-real-arithmetic
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- foundations-refresh.1
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