Complete the magic square below.

For two numbers, $a$ and $b$, the product of the numbers is equal to the product of their LCM and GCF.

$$a \times b = \text{LCM}(a, b) \times \text{GCF}(a, b)$$

Given:
$\text{LCM} = 72$
$\text{GCF} = 6$
One number ($a$) $= 24$
Let the second number be $b$.

$$24 \times b = 72 \times 6$$

$$b = \frac{432}{24}$$ $$b = 18$$

The second number is 18.

$$18$$