Answer
$76,904,685$ ways
Work Step by Step
The order in which the books are chosen is not important.
Combinations, ${}_{n}C_{r}=\displaystyle \frac{n!}{(n-r)!r!}$
${}_{40}C_{8}=\displaystyle \frac{40!}{(40-8)!8!}$
$=\displaystyle \frac{40\times 39\times 38\times 37\times 36\times 35\times 34\times 33}{1\times 2\times 3\times 4\times 5\times 6\times 7\times 8}$
$=\displaystyle \frac{1\times 39\times 19\times 37\times 1\times 5\times 17\times 33}{1\times 1\times 1\times 1\times 1\times 1\times 1\times 1}$
$= 76,904,685$
