SOLUTION: my step-daughter saw an algebra problem that had an exclamation point ( ! )in the expression looking like this ... 4! ... with an answer that the teacher said was correct. What do

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Question 487294: my step-daughter saw an algebra problem that had an exclamation point ( ! )in the expression looking like this ... 4! ... with an answer that the teacher said was correct. What does the ! mean in algebra?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The symbol ! after a number is called "factorial"
For instance, 9! is called "factorial 9"
What you do to find the value of factorial 9 is
to multiply all the digits from 1 to 9
+1%2A2%2A3%2A4%2A5%2A6%2A7%2A8%2A9+=+9%21+
BY my calculator, this is:
+362880+=+9%21+
Factorials are used a lot in probability and
combination problems, like
" How many different ways can 5 people be
seated in 5 chairs?
+1%2A2%2A3%2A4%2A5+=+120+ different ways
That's quicker than writing down all
the possible ways.