Adding, subtracting, multiplying, and dividing fractions

Adding, subtracting, multiplying, and dividing fractions

Amie SchneiderTeacher page

Adding Fractions- Step 1- Make sure both the fractions have a

common denominator. › Example- 1/3 + 1/6 = ?

^Not the same^

Find a common denominator› Multiply 1/3 by 2 on the top and bottom› (2)(1) = 2 (2)(3) = 6› New fraction = 2/6

Adding Fractions- Step 2- Now having common denominators we

can add the fractions

Only add the numerators (top)› 2/6 + 1/6 = › 2 + 1 = 3› Denominator remains 6› Answer 3/6

Adding Fractions- Step 3- If possible simplify your answer

› Does 3/6 equal something else?› Find the greatest common factor› 3/6 = 1/2 because the GCF was 3› 3 ÷ 3 = 1 and 6 ÷ 3 = 2

=

Subtracting Fractions- Step 1- Make sure the denominator are the

same › Example- 1/2 - 1/10 = ?

^Not the same^ Find a common denominator

› Multiply 1/2 by 5› (1)(5) = 5 (2)(5) = 10› New fraction = 5/10

Subtracting Fractions- Step 2- Now that we have common

denominators we can subtract!

Only subtract the numerators.› Example- 5/10 – 1/10 = ?› 5 – 1 = 4› Denominator remains 10› Answer – 4/10

Subtracting Fractions- Step 3- If possible simplify your answer.

› Does 4/10 equal something else?

› Find the greatest common factor› 4/10 = 2/5 because the GCF is 2 › 4 ÷ 2 = 2 and 10 ÷ 2 = 5

Multiplying Fractions- Step 1-

Multiply the numerators

› Example- 1/2 x 2/5 = ?› 1 x 2 = 2

*This time we don’t need a common denominator!

Multiplying Fractions- Step 2-

Multiply the denominators

› Example- 1/2 x 2/5 = ?› 2 x 5 = 10

Multiplying Fractions- Step 3-

If possible simplify your answer

› Answer – 2/10› Find the greatest common factor› 2/10 = 1/5 because the GCF is 2› 2 ÷ 2 = 1 and 10 ÷ 2 = 5

Dividing Fractions- Step 1- “Skip, Change, Flip” Don’t change the first fraction – Skip Change the ÷ to a x - Change Flip the second fraction upside down

(the reciprocal)- Flip

› Example- 1/3 ÷ 2/4 becomes 1/3 x 4/2

Dividing Fractions- Step 2- Multiply the numerators

› 1 x 4 = 4

Multiply the denominators› 3 x 2 = 6

› Answer- 4/6

Dividing Fractions- Step 3-

If possible simplify your answer

› Find greatest common factor› Answer- 4/6› 4/6 = 2/3 because the GCF is 2› 4 ÷ 2 = 2 and 6 ÷ 2 = 3

•Now lets see what you have learned……

#1-What is 2/5 + 1/5? 3/5 3/10 2/25 1/5

Correct! Next Question

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#2-What is 3/4 - 4/6 ? 7/10 1/12 12/24 1/2

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#3-What is 1/2 x 2/3? 3/5 1/6 1/3 2/5

Excellent! Next Question

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#4-What is 1/4 + 2/3? 11/12 3/7 2/12 3/12

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#5- What is 1/3 ÷ 2/3? 1/3 2/6 1/2 2/3

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Nice Try!

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#6- What is 2/5 – 1/3? 2/15 1/15 3/8 1/2

Correct!

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#7- What is 3/4 x 1/8? 3/32 2/4 4/12 3/12

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#8- What is 1/8 ÷ 2/3? 2/24 2/16 3/16 1/5

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Excellent!

The End!