The number of permutations of the 10 letters in the word 'helicopter' is given by the following:
\(\frac{10!}{2!}=10\times9\times8\times7\ times6\times\5\times4\times3=1,814,400\)
Note that the division by 2! is needed because the e's can be arranged in 2! ways without making a different word.
