document.write( "Question 209230: How many different three letter permutations can be formed from the letters in the word clipboard? \n" ); document.write( "
Algebra.Com's Answer #158157 by Theo(13342)\"\" \"About 
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clipboard
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\n" ); document.write( "permutations are an ordered set. this means that the same elements in a different order constitute a different permutation.
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\n" ); document.write( "combinations are an unordered set. this means that the same elements in a different order do not constitute a different combination
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\n" ); document.write( "formulas:
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\n" ); document.write( "number of permutations is \"%28n%29%21+%2F+%28n-x%29%21\"
\n" ); document.write( "number of combinations is \"%28n%29%21+%2F+%28%28x%29%21%2A%28n-x%29%21%29\"
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\n" ); document.write( "example 1
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\n" ); document.write( "form sets of three letter combinations from the letters abcde.
\n" ); document.write( "n = 5
\n" ); document.write( "x = 3
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\n" ); document.write( "they are:
\n" ); document.write( "abc
\n" ); document.write( "abd
\n" ); document.write( "abe
\n" ); document.write( "acd
\n" ); document.write( "ace
\n" ); document.write( "ade
\n" ); document.write( "bcd
\n" ); document.write( "bce
\n" ); document.write( "bde
\n" ); document.write( "cde
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\n" ); document.write( "example 2
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\n" ); document.write( "form sets of three letter permutations from the letters abcde.
\n" ); document.write( "n = 5
\n" ); document.write( "x = 3
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\n" ); document.write( "what is happening here is that for each of the combinations we calculated just above, we have 6 permutations. 10 * 6 = 60 permutations.
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\n" ); document.write( "you get:
\n" ); document.write( "abc * 6
\n" ); document.write( "abd * 6
\n" ); document.write( "abe * 6
\n" ); document.write( "acd * 6
\n" ); document.write( "ace * 6
\n" ); document.write( "ade * 6
\n" ); document.write( "bcd * 6
\n" ); document.write( "bce * 6
\n" ); document.write( "bde * 6
\n" ); document.write( "cde * 6
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\n" ); document.write( "if you look at each one of these combinations and make a permutation out of each one then you get the times 6 factor.
\n" ); document.write( "take the combination abc for example:
\n" ); document.write( "abc
\n" ); document.write( "acb
\n" ); document.write( "bac
\n" ); document.write( "bca
\n" ); document.write( "cab
\n" ); document.write( "cba
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\n" ); document.write( "the one combination of abc yielded 6 permutations of abc.
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\n" ); document.write( "with the combination, all those additional permutations are not allowed because they are each composed of the same letters. with the permutation, however, they are allowed because they are in a different order even though they contain the same combination of letters.
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\n" ); document.write( "the formula for your problem is number of permutations which is:
\n" ); document.write( "\"%28n%29%21+%2F+%28n-x%29%21\"
\n" ); document.write( "the word is clipboard
\n" ); document.write( "n = 9
\n" ); document.write( "x = 3
\n" ); document.write( "n-x = 6
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\n" ); document.write( "your formula becomes:
\n" ); document.write( "\"%289%29%21+%2F+%289-3%29%21\" = \"9%21%2F6%21\" = (9*8*7*6*5*4*3*2*1)/(6*5*4*3*2*1) = 9*8*7 = 504
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\n" ); document.write( "the number of combinations would be the number of permutations divided by x! which in this case is 3! which equals 6 making the number of combinations = 504 / 6 = 84.
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\n" ); document.write( "one of those combinations is:
\n" ); document.write( "cli
\n" ); document.write( "this combination leads to 6 permutations which are:
\n" ); document.write( "cli
\n" ); document.write( "cil
\n" ); document.write( "lic
\n" ); document.write( "lci
\n" ); document.write( "icl
\n" ); document.write( "ilc
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\n" ); document.write( "that happens for each of the 84 combinations to make the total number of permutations = 504.
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