Question

What is the common denominator of 8/9 and 7/8?

Answer 1

Notice that 9 and 8 do not have common factors because:

$\begin{gathered} 9=3^2, \\ 8=2^3\text{.} \end{gathered}$

Therefore the common denominator of 8/9 and 7/8 is:

$9\cdot8=72.$

Answer: 72.