document.write( "Question 1193865: Determine the number of combinations of 20 things, taken four(4) at a time \n" ); document.write( "
Algebra.Com's Answer #825914 by ikleyn(52781)\"\" \"About 
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document.write( "Use the standard formula for the number of combinations\r\n" );
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document.write( "    \"C%5B20%5D%5E4\" = \"20%21%2F%284%21%2A%2820-4%29%21%29\" = \"20%21%2F%284%21%2A16%21%29\".\r\n" );
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document.write( "Reduce common factors 16! in the numerator and the denominator.  The formula takes the form\r\n" );
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document.write( "    \"C%5B20%5D%5E4\" = \"%2820%2A19%2A18%2A17%29%2F%281%2A2%2A3%2A4%29\" = use your calculator = 4845.      ANSWER\r\n" );
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\n" ); document.write( "\n" ); document.write( "This problem is on COMBINATIONS.\r
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\n" ); document.write( "\n" ); document.write( "On  Combinations,  see introductory lessons\r
\n" ); document.write( "\n" ); document.write( "    - Introduction to Combinations\r
\n" ); document.write( "\n" ); document.write( "    - PROOF of the formula on the number of Combinations\r
\n" ); document.write( "\n" ); document.write( "    - Problems on Combinations\r
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\n" ); document.write( "\n" ); document.write( "Also,  you have this free of charge online textbook in ALGEBRA-II in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this online textbook under the topic  \"Combinatorics: Combinations and permutations\". \r
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\n" ); document.write( "\n" ); document.write( "Save the link to this textbook together with its description\r
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\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-II
\n" ); document.write( "https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "into your archive and use when it is needed.\r
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