Determining the Least Common Multiple

This video tutorial introduces the concept of the least common multiple (LCM) and provides three methods to find it: listing multiples, the ladder method, and prime factorization. The instructor explains each method with examples and discusses the pros and cons. Students are encouraged to choose the method that suits them best and practice with provided problems. The video concludes with a summary and credits to artists for fonts and clip arts.

What is required to start learning about LCM?

• Math textbook and ruler

• Computer software

• Writing utensil, math notebook, growth mindset, determination

• Calculator and internet

What is a multiple?

• A number that can only be divided by itself and one

• The sum of two whole numbers

• The result of multiplying a number by a whole number

• The result of dividing a number by a whole number

How can you find the LCM of 4 and 6 using listing multiples?

• Add 4 and 6

• Multiply 4 and 6 directly

• List multiples of 4 and 6 until you find 12

• List multiples of 4 and 6 until you find 24

What is a downside of finding LCM by listing multiples?

• It may require listing many numbers for larger LCMs

• It requires a calculator

• It is too fast

• It is too accurate

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

• Add the numbers together

• Multiply the numbers

• Find a common factor and divide

• List all multiples

What do you do with the numbers outside the ladder in the ladder method?

• Subtract them

• Divide them

• Multiply them

• Ignore them

Tags

CCSS.4.NBT.B.5

What is the first step in using prime factorization to find LCM?

• Add the numbers

• Find the prime factorization of each number

• Multiply the numbers

• List all multiples

How do you use the prime factorizations to find the LCM?

• Add them together

• Divide them

• Line them up and multiply

• Subtract them

What is the LCM of 8 and 12 using prime factorization?

• 48

• 24

• 36

• 16

Which method allows you to choose the one that makes the most sense to you?

• Ladder method only

• Listing multiples only

• Prime factorization only

• Any of the three methods