6 up and 6 down

$\dfrac{\color{#D61F06}{M}}{6}=\dfrac{6}{\color{#3D99F6}{N}}$

is a ratio ; therefore, we can cross multiply ,

$\color{#D61F06}{M}\color{#3D99F6}{N}=36$

Now, we find all the factors of 36,

$\begin{aligned} 1 \times 36 = 36 \\ 2 \times 18 = 36 \\ 3 \times 12 = 36 \\ 4 \times 9 = 36 \\ 6 \times 6 = 36 \end{aligned}$

Now we can reverse the order of the factors for all of the ones listed above, because they are ordered pairs except $6 \times 6$ since it is the same back if we reverse the order.

$4 \times 2 + 1 = 9$

MN = 36 Prime factor of 36 = 2^2 * 3^2 Then, we can find that 36 has 9 factor, ... (2+1) (2+1)=3 3=9