Q1
The common denominator for 1/2 and 1/3 is:
A6
B5
C3
D2
CBSEClass 7 (CBSE)MathematicsCh 11 · Topic 1
Finding a Common Denominator
Learning to find a common denominator to compare or combine fractions.
Core concept
For fractions 1/3 and 1/4, since the LCM of 3 and 4 is 12, both fractions are converted to have a denominator of 12: 1/3 becomes 4/12 (multiplying numerator and denominator by 4), and 1/4 becomes 3/12 (multiplying numerator and denominator by 3). This conversion process, multiplying both the numerator and denominator by the same number, ensures the fraction's actual value remains unchanged even though its appearance (numerator and denominator) changes.
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• A common denominator is a shared multiple of two or more denominators.
• The LCM of the denominators makes the most efficient (smallest) common denominator.
• Converting a fraction to a new denominator: multiply both numerator and denominator by the same number.
• This conversion keeps the fraction's actual value unchanged, just its appearance.