Video Transcript
What fraction equals eight twelvths and has a denominator of 72?
We’re asked to find a fraction which is equal to eight twelvths. We’re told that this fraction has a denominator of 72. We call the number on the bottom of a fraction the denominator. The denominator of eight twelvths is 12. And the denominator of our second fraction is 72. Let’s write that as the bottom number of this fraction.
We know the denominator of both fractions. Now, all we need to do is find the top number, or the numerator, of the second fraction. How many seventy-secondths are equal to eight twelvths? To help us work this out, we need to think about what we did to number 12 to make it into 72. How can we get from 12 to 72?
We know that five times 12 is 60. So, six times 12 must be 72. So, to get from 12 to 72, we have to multiply 12 by six. 12 times six is 72. Now we can multiply the numerator by six as well. This will give us the missing number. What is eight times six? Eight times five is 40. So, eight times six is 48. The numerator is 48. Eight twelvths is equal to 48 over 72. This is the fraction which is equal to eight twelvths and has a denominator of 72, 48 over 72.
