ANSWER

50! /(45! x5!)

$\begin{array}{|rcll|} \hline && \frac{50!}{45!5!} \\ &=& \dbinom{50}{5} \\ &=& \frac{50}{5}\cdot \frac{49}{4}\cdot \frac{48}{3}\cdot \frac{47}{2}\cdot \frac{46}{1} \\ &=& \frac{50}{5}\cdot 49\cdot \frac{48}{12}\cdot \frac{47}{1}\cdot \frac{46}{2} \\ &=&10\cdot 49\cdot 4\cdot 47\cdot 23 \\ &=& \mathbf{2118760} \\ \hline \end{array}$