Ch 2 extends fraction and decimal operations to multiplication and division. Students learn to multiply fractions by whole numbers and by other fractions, divide using reciprocals, and perform similar operations on decimals.
To multiply fractions: multiply numerators together and denominators together: a/b × c/d = (a×c)/(b×d). A fraction multiplied by its reciprocal gives 1. Multiply before simplifying for efficiency.
To divide by a fraction, multiply by its reciprocal: a/b ÷ c/d = a/b × d/c. The reciprocal of a non-zero fraction a/b is b/a. Division by zero is undefined.
To multiply decimals: ignore decimal points, multiply as whole numbers, then place the decimal point in the product (total decimal places = sum of decimal places in both numbers). To divide decimals, convert to whole numbers by multiplying both by appropriate powers of 10.
Download: https://ncert.nic.in/textbook/pdf/gemh102.pdf | Complete book: https://ncert.nic.in/textbook/pdf/gemh1ps.zip
The reciprocal of a fraction a/b is b/a. When you multiply a number by its reciprocal, the product is 1. For example, the reciprocal of 3/4 is 4/3.
Multiply as whole numbers ignoring decimal points, then count the total number of decimal places in both numbers and place the decimal point accordingly in the product.
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