Chapter 10 - Section 10.1 - Sequences and Summation Notation - Exercise Set - Page 1050: 81

$39,800$

Write the correct form as below: We know that $n!=1 \cdot 2 \cdot 3 .....(n-1)n$ Thus, we have $\dfrac{200!}{198!}=\dfrac{1 \cdot 2 \cdot 3 .....198 \cdot 199 \cdot 200}{198!}$ $=\dfrac{(1 \cdot 2 \cdot 3 .....198) \cdot 199 \cdot 200}{198!}$ $=\dfrac{198! \cdot 199 \cdot 900}{198!}$ $=39,800$