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Question 1.
By the definition, n! = 1 * 2 * 3 * 4 * . . . * n.
So, 4! = 1*2*3*4.
You can compute it on your own.
Question 2.
=
this product 1*2*3*4*5 is in the numerator and in the denominator.
So we can cancel it in the numerator and in the denominator.
You will get then
=
,
which is just much easier to calculate.
So, --YOU-- calculate it by hand OR using your calculator.
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At this point, I complete my explanations.