19. In the grid shown the three non-zero numbers in each row, each column and each diagonal multiply to give the same product.
What is the value of $x$ ?

A 36
B 18
C 12
D 9
E 4
19. A Let $p, q, r, s, t$ be missing numbers in the grid, as shown.
Then, comparing the third column with the diagonal running from top right to bottom left: $r \times t \times 3=r \times 6 \times 2$. So $t=4$, as $r$ is non-zero.
Comparing the first column with the diagonal running from top left to bottom right: $p \times s \times 2=p \times 6 \times 3$. So $s=9$, as $p$ is non-zero.

It can now be deduced that the 'magic' product is $9 \times 6 \times 4$. Therefore, considering the bottom row of the grid: $2 \times x \times 3=9 \times 6 \times 4$. Hence $x=9 \times 4=36$.
(It is left as exercise for the reader to complete the square.)