MathematicsClass 7Fractions and Decimals
Multiplication of Fractions
Multiplying whole numbers by fractions, proper fractions, and improper fractions.
Class 7 · MathematicsCBSE & ICSE SOF IMO
Definition
Multiplication of fractions involves multiplying the numerators together to get the new numerator and the denominators together to get the new denominator. For mixed numbers, it is first necessary to convert them into improper fractions before multiplying. Simplifying the fraction before or after multiplication makes the calculation easier.
Key formula
Numerator times Numerator over Denominator times Denominator
Worked examples
1
Multiply 2/3 by 4/5: (2 times 4) / (3 times 5) = 8/15
2
Multiply 3/4 by 8/9: (3 times 8) / (4 times 9) = 24/36 = 2/3
3
Multiply 1 and 1/2 by 2/3: Convert to 3/2 times 2/3 = 6/6 = 1
Common mistakes
- • Finding a common denominator before multiplying fractions, which is only necessary for addition and subtraction.
- • Forgetting to convert mixed fractions into improper fractions before performing the multiplication.