Convert 5 N/mm to mm/N

Question

My child was asked to convert a number to units in mm/N, from the number $5$ N/mm. How can I swap units from the denominator to the numerator? I appreciate any help you can provide.

Answer 1

Note that $$ \frac{1}{\text{N}/\text{mm}} = \frac{\text{mm}}{\text{N}} $$