Multiplication of fractions PowerPoint.pdf
Multiplication of fractions PowerPoint.pdf
Multiplication of fractions PowerPoint.pdf
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Fractions XIV<br />
<strong>Multiplication</strong> <strong>of</strong> Fractions<br />
by Monica Yuskaitis
Times You Would Multiply a<br />
Fraction Times a Fraction<br />
• Your family eats 1/8 <strong>of</strong> 1/2 <strong>of</strong> a left<br />
over wedding cake.<br />
1/8 <strong>of</strong> 1/2 or 1/8 x 1/2<br />
Copyright © 2000 by Monica Yuskaitis
Times You Would Multiply a<br />
Fraction Times a Fraction<br />
•Jose had already read 1/2 <strong>of</strong> his novel.<br />
Today he read 1/12 <strong>of</strong> the 1/2 left.<br />
How much <strong>of</strong> the book has he read?<br />
1/12 <strong>of</strong> 1/2 or 1/12 x 1/2<br />
Copyright © 2000 by Monica Yuskaitis
Multiplying Fractions<br />
Conceptual Understanding<br />
•When you multiply two <strong>fractions</strong> that<br />
are between 0 and 1 the product is<br />
smaller than both <strong>fractions</strong>.<br />
½ x ¾ = 3/8<br />
Look at the diagram on the<br />
next slide to understand why.<br />
Copyright © 2000 by Monica Yuskaitis
Multiplying Fractions<br />
Conceptual Understanding<br />
½ x ¾ = 3/8<br />
¼ ¼ ¼ ¼<br />
1/8 1/8 1/8<br />
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction <strong>of</strong> a<br />
Fraction<br />
• The first thing to remember is “<strong>of</strong>”<br />
means multiply in mathematics.<br />
<strong>of</strong> =<br />
x<br />
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction <strong>of</strong> a<br />
Fraction<br />
• Step 1 - When you see a fraction<br />
problem you know when you read “<strong>of</strong>”<br />
in the problem you multiply.<br />
1<br />
2<br />
x<br />
<strong>of</strong><br />
4<br />
9<br />
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction <strong>of</strong> a<br />
Fraction<br />
• Step 2 – Multiply your numerators<br />
straight across.<br />
1<br />
2<br />
x 4<br />
9<br />
= 4<br />
Copyright © 2000 by Monica Yuskaitis
How to Find a Fraction <strong>of</strong> a<br />
Fraction<br />
• Step 3 – Then multiply your<br />
denominators straight across.<br />
1<br />
2<br />
x 4<br />
9<br />
= 4<br />
18<br />
Copyright © 2000 by Monica Yuskaitis
How to Find the Fraction <strong>of</strong> a<br />
Fraction<br />
• Step 4 – Simplify your answer. In<br />
this case we reduce.<br />
1<br />
2<br />
x 4<br />
9<br />
= 4<br />
18 ÷<br />
÷<br />
2<br />
2 = 2<br />
9<br />
Copyright © 2000 by Monica Yuskaitis
Multiply and Simplify<br />
1<br />
6<br />
<strong>of</strong><br />
9<br />
5<br />
x ÷<br />
3 3<br />
30 ÷ 3 = 10<br />
= 9<br />
Copyright © 2000 by Monica Yuskaitis
Multiply and Simplify<br />
8<br />
9<br />
<strong>of</strong><br />
3<br />
4<br />
24 12 2<br />
=<br />
36 12 = 3<br />
x ÷<br />
÷<br />
Copyright © 2000 by Monica Yuskaitis
Multiply and Simplify<br />
7<br />
2<br />
<strong>of</strong> x<br />
4 4<br />
6 ÷<br />
÷<br />
4<br />
3<br />
= 28 4<br />
6 6) 28<br />
2 24<br />
2 = 4 2<br />
3 4<br />
Copyright © 2000 by Monica Yuskaitis
Multiply and Simplify<br />
3<br />
3<br />
<strong>of</strong> x<br />
9<br />
= 27<br />
3<br />
8<br />
4<br />
2<br />
8 8) 27<br />
24<br />
3<br />
Copyright © 2000 by Monica Yuskaitis
Multiply and Simplify<br />
7<br />
3<br />
<strong>of</strong> x<br />
8<br />
2<br />
9 2 ÷ 2<br />
6 2 = 9 1<br />
÷<br />
= 56 9<br />
6 6) 56<br />
54<br />
3 2<br />
2<br />
6<br />
Copyright © 2000 by Monica Yuskaitis
4<br />
2<br />
Multiply and Simplify<br />
<strong>of</strong> x<br />
3<br />
4<br />
1 4 ÷ 4<br />
8 4 = 1 1<br />
÷<br />
Super job!<br />
= 12 1<br />
8 8) 12<br />
8<br />
2 4<br />
4<br />
8<br />
Copyright © 2000 by Monica Yuskaitis
Credits<br />
Clipart from “Micros<strong>of</strong>t Clip<br />
Gallery” located on the Internet<br />
at http://cgl.micros<strong>of</strong>t.com/<br />
clipgallerylive/default.asp<br />
Copyright © 2000 by Monica Yuskaitis
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