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source: ncert
topic: arithmetic
class_level: class_7
chapter: ch2
difficulty: beginner
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Class 7 | Ch2: Fractions and Decimals
Multiplication of fractions: (a/b)×(c/d)=ac/bd. Convert mixed to improper first.
2(3/4)×1(1/3) = (11/4)×(4/3) = 44/12 = 11/3 = 3(2/3).
Division: a/b ÷ c/d = a/b × d/c (multiply by RECIPROCAL of second).
3(1/2)÷1(2/3) = (7/2)÷(5/3) = (7/2)×(3/5) = 21/10 = 2.1.
Decimal multiplication: count total decimal places. 0.4×0.3=0.12 (1+1=2 places).
Division by decimal: 2.4÷0.6 = 24÷6 = 4 (multiply both by 10).
Conversion: 0.125=125/1000=1/8. 1.625=1625/1000=13/8=1(5/8).
Common mistake: flip SECOND fraction not first when dividing fractions. |