How do you write $18\% $ as a fraction?

Hint:
For converting percent into fractions we divide numbers by $100$. And after that, we just cancel out common factors from numerator and denominator.

Complete step by step answer:
We convert a percent into a fraction
For that,
Write down the percent divided by $100$,
$\dfrac{{18}}{{100}}$
Now, sometimes here you will get the right answer but in this question, we have to simplify $\dfrac{{18}}{{100}}$.
For simplifying $\dfrac{{18}}{{100}}$ we have to find common factors from numerator and denominator,
Here, the common factor is $2$
$ \Rightarrow \dfrac{{9 \times 2}}{{50 \times 2}}$
So here we have to cancel out $2$ from numerator and denominator,
After canceling $2$ from numerator and denominator we get,
$ \Rightarrow \dfrac{9}{{50}}$

After converting and simplifying we will get $\dfrac{9}{{50}}$ as an answer.

Note:
In this type of question if you forget to cancel out common factors from the numerator and denominator your answer will be wrong. So always remember to convert fraction numbers to the simplest form.