WALT: Find the Lowest Common Multiple

What are the multiples of:

• 5

• 10

• 7

• 18

How do we know if a number is a multiple of:

• 2

• 4

• 5

• 10

• 100

Are the following numbers multiples of 2?

• 246

• 1067

• 20000

• Three million

Are the following numbers multiples of 4?

• 300

• 235

• 410

• Five hundred and thirty two

Are the following numbers multiples of 5?

• 1000

• 25456

• 5555

• 1025

• Three million two hundred and fifty six

Which of the numbers below are multiples of both 2 AND 5?

20 40 45 9076

105 200 305 40 42

Give three numbers which are multiples of 2 and 5.What can you say about numbers which are multiples of 2 and 5?

What is a Lowest Common Multiple?

• Consider the numbers 2 and 5

• The lowest common multiple is the smallest number which is the multiple of both.

• Multiples of 2 are: 2, 4, 6, 8, 10, 12, 14, …• Multiples of 5 are: 5, 10, 15, 20, 25, …

• Which is the smallest number that occurs in BOTH lists?

• This is the LOWEST COMMON MULITPLE.

What is the LOWEST COMMON MULTIPLE of:

• 2 and 7

• 3 and 7

• 5 and 3

• 5 and 7

Question:

• Decide with your partner the answer to the question below. You must EXPLAIN your answer and give examples.

• Is the lowest common multiple of two numbers always found by multiplying those two numbers together?

• E.g LCM of 2 and 7 is 2 x 7 = 14

Find the LCM of:

• 4 and 40

• 4 and 8

• 4 and 6

• 12 and 4

Design a poster

• Make a poster explaining what the Lowest Common Multiple of a pair of number is.

• Make sure you give some examples

• Give a method for finding the LCM.