This chapter covers lowest common multiple. It covers how to find the lowest common multiple (LCM) of two numbers and using the LCM to compare fractions.
The lowest common multiple (LCM) of given numbers is the number that appears in both the given numbers times table. Suppose we wanted to find the lowest common multiple of 3 and 4. First we would list the 3 times table; That is…
Then list the 4 times table….
Above we can see that the first number which appears in both is 12. We can conclude that;
12 is the lowest common multiple of 3 and 4.
Example 2
This example involves harder numbers. Suppose we wanted to find the LCM of 18 and 42.
First let’s list a few multiples of the highest number (42) because it is very likely that the multiple for the smallest number will be in the first few multiples of the larger number.
Now let’s list the multiples of 18 and continue until there is a number which appears in the list above.
126 appears in the first list so we can conclude that;
126 is the lowest common multiple of 18 and 42.