# If I have a 20 sided dice and roll it twice, what are the odds that I will roll the same number twice?

It depends on the condition... Perhaps $\frac{1}{20}$ is more suitable.
In this situation, the probability of getting the $\textcolor{red}{\text{given}}$ number twice, for example, rolling a $1$ twice, will be $\frac{1}{20} \cdot \frac{1}{20} = \frac{1}{400.}$
However, the probability of rolling $\textcolor{b l u e}{\text{freely selected}}$ number twice, i.e. any of two 1s, two 2s, ...two 20s, will be $\frac{1}{400} \cdot 20 = \frac{1}{20}$.