Adding and Subtracting with Least Common Denominator

The video tutorial explains how to work with fractions by changing them to have the same denominator, focusing on the least common denominator (LCD). It provides examples of comparing, adding, and subtracting fractions using the LCD and quick common denominators. The tutorial also covers simplifying fractions and highlights the importance of using the least common multiple (LCM) for efficient calculations.

Why is it useful to change fractions to have the same denominator?

• To easily compare, add, or subtract them

• To simplify the fractions

• To convert them to decimals

• To make the numerators equal

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CCSS.4.NF.A.2

What does LCD stand for in the context of fractions?

• Largest Common Denominator

• Lowest Common Denominator

• Last Common Denominator

• Least Common Denominator

What is the least common multiple (LCM) of 12 and 8?

• 24

• 16

• 48

• 32

How do you convert 5/12 to have a denominator of 24?

• Multiply both numerator and denominator by 4

• Multiply both numerator and denominator by 3

• Multiply both numerator and denominator by 2

• Multiply both numerator and denominator by 6

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CCSS.3.NF.A.3B

CCSS.4.NF.A.1

What is the equivalent fraction of 3/8 with a denominator of 24?

• 6/24

• 18/24

• 12/24

• 9/24

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CCSS.3.NF.A.3B

CCSS.4.NF.A.1

Why can't you directly add 1/4 and 5/6?

• They have different numerators

• They are already simplified

• They have different denominators

• They are improper fractions

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CCSS.5.NF.A.1

CCSS.5.NF.A.2

What is the quick common denominator for 1/4 and 5/6?

• 12

• 24

• 30

• 18

What is the result of adding 1/4 and 5/6 using the least common denominator?

• 1 1/12

• 1 2/12

• 1 3/12

• 1 4/12

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CCSS.5.NF.A.1

CCSS.5.NF.A.2

What is the least common multiple of 3 and 9?

• 12

• 9

• 6

• 3

What is the simplified form of 12/27?

• 3/9

• 2/9

• 4/9

• 1/9