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VOCABULARY Denominator: The bottom number in a fraction Multiple: The product of any number and a whole number is a multiple of that number

VOCABULARY Least Common Multiple: The smallest number, other than zero, that is a multiple of two or more given numbers.

PURPOSE OF COMMON DENOMINATORS When we compare amounts, we need to convert the amounts to a common currency to compare them. This is true with fractions too. We need to divide them up into same-sized slices so that we can compare the number of slices in one to the number of slices in another. We use common denominators when adding and subtracting fractions.

METHOD 1 1.List the multiples of each denominator. 2.Choose the smallest number that appears in each list.

METHOD 2 1. Multiply the denominators. ***This method will require more simplifying than #1.

REWRITING FRACTIONS WITH A COMMON DENOMINATOR 1.Rewrite both fractions with the common denominator. 2.Change to equivalent fractions by multiplying the top number by the same number that you multiplied by the bottom number to get the common denominator.

EXAMPLES: Find a Common Denominator 1.6, 5 2.3, 4 3.4, 6 4.8, 12

EXAMPLES: REWRITE AS FRACTIONS WITH COMMON DENOMINATORS 5. 3/8, ½ 6. 5/6, 1/9

EXAMPLES: REWRITE AS FRACTIONS WITH COMMON DENOMINATORS 7. ½, ¾ 8. 3/10, 5/8

Rules Situation: Same Denominator Rules: Compare the numerators Examples: 5/10 > 3/10 1/5 < 2/5 3/12 = 3/12

Rules Situation: Different Denominators Rules: Find a common denominator and then compare the numerators Example: 1.) 1/5 = 6/30 6/30 > 5/30 1/6 = 5/30 2.) 1/4 = 5/20 5/20 < 8/20 2/5 = 8/20

Examples Put the appropriate sign between the fractions. 1.) 5/6 __ 3/6 4.) 2/7 __ 3/5 2.) 2/4 __ 3/4 5.) 4/5 __ 3/4 3.) 4/ 9 __ 5/9 6.) 3/5 __ 4/10

Practice Put the appropriate sign between the fractions. 1.) 2/6 __ 4/6 4.) 4/8 __ 5/7 2.) 3/4 __ 2/4 5.) 1/4 __ 2/3 3.) 5/ 9 __ 3/9 6.) 2/5 __ 4/10

Exit Ticket 1.) 2/5 __ 4/5 4.) 5/9 __ 5/6 2.) 3/9 __ 6/9 5.) 4/5 __ 2/6 3.) 5/ 12 __ 3/12 6.) 2/8 __ 4/5