Least Common Multiples and Least Common Denominator

Front

Here are the first ten multiples of 3 and 5. 3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30 5: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 Which multiple is the Least Common Multiple (LCM) of 3 and 5?

Back

15

Answer explanation

15 and 20 are both common multiples of 3 and 5! But the LEAST common multiple is 15 because 15 is less than 20 and the first multiple that has the factors 3 and 5.

Front

What is the Least Common Multiple (LCM) of 4 and 5?

Back

The LCM is 20

Answer explanation

The LCM of 4 and 5 is 20! It's the first multiple on both lists and has the factor 4 and 5.

Front

What is the Least Common Multiple (LCM) of 2 and 4? 2: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 4: 4, 8, 12, 16, 20, 24, 28, 32, 36, 40 (Hint! Look for the first number that is the same on both lists!)

Back

4

Answer explanation

The LCM of 2 and 4 is 4! It's the first multiple that is the same on both lists and has the factors 2 and 4!

Fun fact! All the multiples of 4 are common multiples of 2 because all the multiples of 4 are even numbers!

Front

LCM of 3 and 6

Back

6

Answer explanation

The LCM of 3 and 6 is 6!

Fun fact! All the multiples of 6 are also common multiples of 3!

Front

LCM of 10 and 12

Back

60

Answer explanation

The LCM for 10 and 12 is 60!

Fun fact! If you are trying to find the least common multiple of a number and 10, look for the first multiple of the other number that ends with a zero!

Front

What is the LCM of 12 and 20?

Back

60

Answer explanation

The LCM of 12 and 20 is also 60!

Front

How do you feel about finding the Least Common Denominator (LCD) of two fractions using Least Common Multiple (LCM)?

Back

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Front

What is the Least Common Denominator (LCD) of the fractions 1/2 and 1/4?

Back

The LCD is 4

Answer explanation

The least common multiple of 2 and 4 was 4!

So the least common denominator of 1/2 and 1/4 is also 4!

Front

Equivalent fraction of 1/2 with 4 as denominator?

Back

2/4

Answer explanation

If you multiply the numerator and denominator of 1/2 by 2, you will get 2/4 which has 4 as the denominator.

1/2 is equivalent to 2/4.

Tags

CCSS.3.NF.A.3B

CCSS.4.NF.A.1

Front

"They are fractions with common denominators because..."

Back

both 2/4 and 1/4 have 4 as the denominator.

Tags

CCSS.3.NF.A.3D