718. Let's return to the example where the common measure fits into one segment 15 times, and into another 12 times. Can we find a larger segment that would also be a common measure?
$\triangleright$ Yes: $15=3 \cdot 5$, and $12=3 \cdot 4$, so if we take a common measure three times longer, it will fit (respectively) 5 times and 4 times. $\triangleleft$

In this example, we managed to find a larger common measure; a smaller one can always be found (it is enough to divide the common measure into several equal parts).