Question

Which number is not a common multiple of 8 and 16?

Answer 1

Let's list the multiples of 8 and 16.

$\text{Multiples of 8:}$
$8,16,24,32,40,48,56,64,72,80,88,96,104,112,120$

$\text{Multiples of 16:}$
$16,32,48,64,80,96,112,128,144,160,176,192,208$

Thus, we can see that 72 is not a common multiple of 8 and 16 as it is not a multiple of 16.