What is the lowest common denominator of 8 and 9?

The lowest common denominator of 8 and 9 is 72. This is because the least common multiple (LCM) of 8 and 9 is 72, which is also the lowest common denominator when working with fractions that have 8 and 9 as the denominators. To find the lowest common denominator, you can find the LCM of the two numbers and use that as the denominator when adding, subtracting, multiplying, or dividing fractions with those denominators.