Multiplying and Dividing Fractions 7 th Grade Math

$A Quick Review: n KEY POINT when multiplying or dividing fractions: Change a mixed$

More on Multiplying Fractions: n n “of” means multiply! Example: n There are 8

$Multiplying Fractions: n n Multiplying fractions is easier than adding or subtraction because you$

A Few Examples: n Example #1: 2/3 X 4/5 n n n Example #2:

Make Life Easier!! Cross Reduce n n When multiplying, you can simplify your factors

What in the World is a “Reciprocal”? n Reciprocal: n n n When two

Algorithm: Dividing Fractions n Remember these three words: n KEEP, CHANGE, RECIPROCAL KEEP First

Some Examples: n Example #1: n Example #2: n Example #3: n Example #4:

“Card and Domino Multiplication/Division” n n Each partner draws one (1) card and one

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Multiplying and Dividing Fractions 7 th Grade Math August, 2013

$A Quick Review: n KEY POINT when multiplying or dividing fractions: Change a mixed$

A Quick Review: n KEY POINT when multiplying or dividing fractions: Change a mixed number into an improper fraction, n Still simplify your answer.

More on Multiplying Fractions: n n “of” means multiply! Example: n There are 8 cars in Michael’s toy collection. 1/2 of the cars are red. How many red cars does Michael have? n n This problem is asking “What is 1/2 of 8? ” A way to answer it is to put a multiplication sign in place of “of. ” You then get 1/2 x 8 or 8 x ½ (remember that multiplication is commutative).

$Multiplying Fractions: n n Multiplying fractions is easier than adding or subtraction because you$

Multiplying Fractions: n n Multiplying fractions is easier than adding or subtraction because you don’t need to find common denominators. YAY!!!!!! Just multiply straight across. n n Multiply numerators Then, multiply denominators

A Few Examples: n Example #1: 2/3 X 4/5 n n n Example #2: 9/2 X 3/7 n Answer: 27/14=1 13/14 Example #3: 2 1/6 X 3/2 n n Answer: 39/12=3 3/12=3 ¼ Example #4: 5 X 2/7 n n Answer: 8/15 Answer: 10/7=1 3/7 Example #5: 5 1/3 • 9 ½ n Answer: 50 2/3

Make Life Easier!! Cross Reduce n n When multiplying, you can simplify your factors by “cross reducing”. Examples: n 6/35 • 5/24 n 2/15 • 3/18 n 1/8 (4/5)

What in the World is a “Reciprocal”? n Reciprocal: n n n When two fractions are multiplied and their product is 1. AKA “inverting” or “flipping” a number Examples: n The reciprocal of ½ is _______. n The reciprocal of 1 ¾ is _______. n The reciprocal of 8 is ____.

Algorithm: Dividing Fractions n Remember these three words: n KEEP, CHANGE, RECIPROCAL KEEP First fraction n CHANGE Division to multiplication n RECIPROCAL of last fraction n Multiply and Simplify n

Some Examples: n Example #1: n Example #2: n Example #3: n Example #4: Don’t forget to cross reduce if possible ONLY when multiplying!

“Card and Domino Multiplication/Division” n n Each partner draws one (1) card and one (1) domino n Card = whole number n Domino = fraction Multiply your two numbers (individually) Divide your two numbers (individually) Compare your answers. If you both have the same answer, give your team a point for each problem. Highest points (with work shown) wins candy!