Arithmetic with fractions
Fraction arithmetic preserves value by using common denominators or reciprocals.
Key knowledge
Add or subtract fractions after converting them to a common denominator; multiply their numerators and denominators. To divide by a nonzero fraction, multiply by its reciprocal. A product denominator works even when it is not the least common denominator.
Values and equations
a/b ± c/d = (ad ± bc)/(bd); (a/b)(c/d) = ac/(bd); (a/b)/(c/d) = ad/(bc)
- a, c
- Integer numerators; c≠0 for division
- b, d
- Nonzero integer denominators
Conditions and scope
- The formulas use integer numerators and nonzero integer denominators.
- Division additionally requires the divisor's numerator c≠0.
Denominator and divisor restrictions retained. Product denominator is a valid common denominator; it need not be least. Directly inspected mathematical section only; historical narrative and the number-line recipe for negative denominators excluded.
Sources · 3
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Lynn Marecek, MaryAnne Anthony-Smith and Andrea Honeycutt Mathis / OpenStax2 sources
- Ganita Manjari, Grade 9 Part I, 3.4: Fractions and Rational NumbersNCERT, IndiaReference guide · PDF
Evidence and review
Checked the stated arithmetic with fractions 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-fraction-arithmetic
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions