Finding LCM for Three Numbers Using the Ladder Method

This video tutorial introduces the ladder method for finding the least common multiple (LCM) of numbers. It provides step-by-step examples for calculating the LCM of different sets of numbers, such as 6, 8, and 10, as well as 12, 15, and 20. The tutorial also includes a practice problem for viewers to solve on their own, demonstrating the method's flexibility and ease of use. The video concludes with encouragement to apply the ladder method in future LCM calculations.

What is the first step in the ladder method for finding the LCM?

• List all multiples of the numbers.

• Multiply all the numbers.

• Draw a sideways L shape.

• Choose a factor that divides evenly into all numbers.

Which factor is chosen first when finding the LCM of 6, 8, and 10?

• 5

• 2

• 4

• 3

What is the LCM of 6, 8, and 10?

• 240

• 60

• 120

• 180

Which factor is chosen first when finding the LCM of 12, 15, and 20?

• 2

• 3

• 4

• 5

What is the LCM of 12, 15, and 20?

• 75

• 60

• 45

• 30

What is the next step after dividing the numbers by the chosen factor in the ladder method?

• Draw another ladder.

• Choose another factor.

• Multiply the results.

• List the multiples.

Tags

CCSS.4.OA.B.4

Which factor is chosen first when finding the LCM of 7, 18, and 21?

• 3

• 7

• 2

• 5

What is the LCM of 7, 18, and 21?

• 84

• 210

• 126

• 168

What should you do if a factor does not divide evenly into a number in the ladder method?

• Choose a different factor.

• Multiply the number.

• Skip the number.

• Bring the number down.

Tags

CCSS.4.OA.C.5

What is the final step in the ladder method for finding the LCM?

• Add all the numbers.

• Divide the numbers again.

• Multiply all the factors outside the ladder.

• List all the multiples.