#### Answer

900

#### Work Step by Step

$n!=n(n-1)(n-2)\cdots(3)(2)(1)$
and, by definition, $0!=1$
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Most calculators can display up to $69!\approx 10^{98}$.
Anything over results in an error.
900! and 899! are huge numbers.
We employ a different approach:
$900!=900\times 899\times 898\times...\times 2\times 1$
$=900\times 899!$
So, we write
$\displaystyle \frac{900!}{899!}=\frac{900\times 899!}{899!}$
... reduce the fraction by $899! $...
$=900$