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Lesson 2 — Activity 1: Lowest Common Multiple (LCM)
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Lesson 2 — Activity 1: Lowest Common Multiple (LCM)
Getting Ready
When you completed the last activity on scientific notation, you first practised writing multiples of 10 (100 = 10 x 10)
Multiples are the product (answer) of a known number and a whole number. For example, to find the first five multiples of the number 2, you would do the following:
 2 x 1 = 2

2 x 2 = 4

2 x 3 = 6

2 x 4 = 8
2 x 5 = 10
2 x 5 = 10
The multiples of 2 are: {2, 4, 6, 8, 10}
Try This:
What are the first five multiples of the number 3?
 3 x 1 = 3

3 x 2 = 6

3 x 3 = 9

3 x 4 = 12

3 x 5 = 15
The multiples of 3 are: {3, 6, 9, 12, 15}
Sometimes it is important to know what the lowest common number is between two different numbers.
For example, let's say you are having some friends over. You want everyone to get the same amount of snacks. You want to purchase chocolate bars that come in packages of 4 and drinks that comes in packages of 6.
How many packages of chocolate bars and drinks do you need to buy so that you have the same amount of each?
You could make a table and look for a common number.
Product 
1 Package

2 Packages

3 Packages

4 Packages

Chocolate Bars 
4  8  12  16 
Drinks 
6 
12

18  24 
Looking at the table, you can see that 12 is the common number.
This means you need to buy 3 packages of chocolate bars and 2 packages of drinks.
Looking at the table, you can see that 12 is the common number.
This means you need to buy 3 packages of chocolate bars and 2 packages of drinks.
This means you need to buy 3 packages of chocolate bars and 2 packages of drinks.
Making a table like this can be timeconsuming. Another way is to use the lowest common multiple (LCM).
Calculating
the lowest common multiple is similar to the chart but much faster. All
you do is list the multiples of each number until you find a common
number. This common number is the lowest common multiple.
Let's look at the numbers 3 and 5. What is the lowest common multiple for 3 and 5?
The easiest way is to list the multiples like this:
The LCM for 3 and 5 is 15.
