document.write( "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? \n" ); document.write( "

Algebra.Com's Answer #333023 by josmiceli(19441) $\"\"$ $\"About$

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The symbol ! after a number is called \"factorial\"
\n" ); document.write( "For instance, 9! is called \"factorial 9\"
\n" ); document.write( "What you do to find the value of factorial 9 is
\n" ); document.write( "to multiply all the digits from 1 to 9
\n" ); document.write( " $\"+1%2A2%2A3%2A4%2A5%2A6%2A7%2A8%2A9+=+9%21+\"$
\n" ); document.write( "BY my calculator, this is:
\n" ); document.write( " $\"+362880+=+9%21+\"$
\n" ); document.write( "Factorials are used a lot in probability and
\n" ); document.write( "combination problems, like
\n" ); document.write( "\" How many different ways can 5 people be
\n" ); document.write( "seated in 5 chairs?
\n" ); document.write( " $\"+1%2A2%2A3%2A4%2A5+=+120+\"$ different ways
\n" ); document.write( "That's quicker than writing down all
\n" ); document.write( "the possible ways. \n" ); document.write( "

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