So we want to write a fraction that is less than 5/6 and has a denominator of 8. So lets start from 1/1 that is greater then 5/6 and doesn't have 8 as a denominator. Lets take one half from 1/1 and well get 1/2. Now we have a fraction that is lesser than 5/6 but still dont have 8 in the denominator. Now, lets take one half from 1/2. That is 1/4. Now we are getting closer and we need to take one more half from 1/4 and then we get 1/8 which is less then 5/6 and has 8 in the denominator.
