Key Points
Working with Fractions
Multiplying a Fraction by a Whole Number
To multiply a fraction by a whole number, multiply the whole number with the numerator and keep the denominator the same. For example, .
Multiplication of a Fraction by a Whole Number
To multiply a fraction by a whole number, multiply the whole number with the numerator of the fraction, keeping the denominator the same. The formula is .
Multiplication of Two Fractions
To multiply two fractions, multiply their numerators together and their denominators together. The general formula is .
Multiplication of Two Fractions
The product of two fractions is found by multiplying their numerators together and their denominators together. This general rule is given by the formula .
The Meaning of 'Of' in Fraction Problems
The word 'of' represents multiplication when used with fractions. For example, finding of 20 means calculating .
Multiplying Mixed Fractions
To multiply mixed fractions, you must first convert each mixed fraction into an improper fraction. After converting, multiply the resulting improper fractions using the standard rule.
Simplifying Before Multiplying
Before multiplying fractions, you can simplify by dividing any numerator and any denominator by their common factors. This process is called cancellation and makes calculations easier.
Simplifying by Cancelling Common Factors
Before multiplying fractions, you can simplify by dividing any numerator and any denominator by their common factors. This process, called cancelling, makes the final multiplication easier.
The Meaning of 'Of' in Fraction Problems
In word problems, the term 'of' signifies multiplication. For example, finding of 20 is the same as calculating .
Reciprocal of a Fraction
The reciprocal of a fraction is found by inverting it, which means swapping the numerator and the denominator. The reciprocal of is , provided and .
Product of a Fraction and its Reciprocal
The product of any non-zero fraction and its reciprocal is always 1. For example, .
Value of the Product of Fractions
When you multiply two proper fractions (values between 0 and 1), the product is smaller than both of the original fractions. If you multiply a number greater than 1 by a proper fraction, the product will be smaller than the original number.
Reciprocal of a Fraction
The reciprocal of a fraction is obtained by swapping its numerator and denominator. The reciprocal of is , where and . The product of any fraction and its reciprocal is always 1.
Division of Fractions Rule
To divide one fraction by another, you multiply the first fraction (the dividend) by the reciprocal of the second fraction (the divisor). This is often called the 'invert and multiply' rule.
General Formula for Fraction Division
The formula for dividing fractions is . Remember to only invert the fraction you are dividing by.
Division of Fractions
To divide one fraction by another, you multiply the first fraction (the dividend) by the reciprocal of the second fraction (the divisor). The rule is .
Operations with Mixed Fractions
Before multiplying or dividing mixed fractions, you must first convert them into improper fractions. For example, to calculate , first convert to .
Dividing a Fraction by a Whole Number
To divide a fraction by a whole number, multiply the fraction by the reciprocal of the whole number. For example, .
Product Size in Fraction Multiplication
When you multiply two proper fractions (values between 0 and 1), the product is always smaller than both of the original fractions. For example, , and is smaller than both and .
Dividing a Whole Number by a Fraction
To divide a whole number by a fraction, multiply the whole number by the reciprocal of the fraction. For example, .
Value of the Quotient in Division
When the divisor is a proper fraction (between 0 and 1), the quotient will be greater than the dividend. When the divisor is greater than 1, the quotient will be less than the dividend.
Quotient Size in Fraction Division
When you divide by a proper fraction (a number between 0 and 1), the quotient is greater than the dividend. For example, , and the result is greater than the dividend .
Commutative Property of Multiplication
The order of multiplication for fractions does not affect the final product. This means that is equal to .
Commutative Property of Multiplication
The order in which you multiply fractions does not change the result, which is the commutative property: . Division, however, is not commutative.
Quick Revision Tips
- • Review these points before exams
- • Make flashcards for better retention
- • Connect points to real-world examples
- • Practice explaining each point in your own words