document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=412774>Question 412774</A>: <I><SPAN STYLE=\"word-break: break-all;\"> How many 4-letter code words are possible using the first 8 letters of the alphabet when letters are allowed to repeat?\r<BR>\n" );
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document.write( "I know the answer is 4096, but what is the answer when you cannot repeat letters? and how did you get given answer? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #289937 by </B><A HREF=/tutors/aboutme.mpl?userid=sudhanshu_kmr><B>sudhanshu_kmr(1152)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=sudhanshu_kmr><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/cgi-bin/show-face.mpl?user=sudhanshu_kmr><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=289937\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <BR>\n" );
document.write( "no. of possible code words when repetition allowed = 8 * 8 * 8 * 8 = 4096\r<BR>\n" );
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document.write( "no. of possible code, when repetition is not allowed = 8P4 = 1680\r<BR>\n" );
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document.write( "as repetition is not allowed, \r<BR>\n" );
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document.write( "         no. of ways to arrange 4 letters out of 8 = 8P4 \r<BR>\n" );
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document.write( "another ways,  \r<BR>\n" );
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document.write( "no. of ways to choose  first letter for code = 8 \r<BR>\n" );
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document.write( "no. of ways to choose second letter for code = 7 (except the first one )\r<BR>\n" );
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document.write( "similarly, no. of ways to choose third and fourth letter are 6 and 5.\r<BR>\n" );
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document.write( "total no. of ways = 8*7*6*5 = 1680\r<BR>\n" );
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document.write( " \r<BR>\n" );
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document.write( " </SPAN>\n" );
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