Without using a calculator, find the value of:

$\frac{10!}{8!}+\frac{9!}{7!}$

Without using $a$ calculator, find the value of:

$\frac{20!}{18!}-\frac{13!}{11!}$

Use your calculator to find the smallest value of $n$ for which:

$n !>1000000$

Use your calculator to find the smallest value of $n$ for which:

$5!\times 6!<n!$

Use your calculator to find the smallest value of $n$ for which:

$\left(n!\right)!>{10}^{20}$

Use your calculator to find the largest value of $n$ for which:

$\frac{n!}{500000}<80$

Use your calculator to find the largest value of $n$ for which:

$1.5\times {10}^{12}-n!>0$

Use your calculator to find the largest value of $n$ for which:

$\frac{n!}{(n-2)!}<500$