document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=511670>Question 511670</A>: <I><SPAN STYLE=\"word-break: break-all;\"> from the ten books that you've recently bought but not read, you plan to take 4 with you on vacation. how many different sets of 4 books can you take? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #342347 by </B><A HREF=/tutors/aboutme.mpl?userid=Maths68><B>Maths68(1474)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Maths68><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=Maths68><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=342347\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Use<BR>\n" );
document.write( "nCr=n!/r!(n-r)!<BR>\n" );
document.write( "Here<BR>\n" );
document.write( "n=10<BR>\n" );
document.write( "r=4\r<BR>\n" );
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document.write( "Total number of sets of 4 books = 10!/4!(10-4)!<BR>\n" );
document.write( "Total number of sets of 4 books = 10!/4!(6)!<BR>\n" );
document.write( "Total number of sets of 4 books = 10*9*8*7*6!/4!(6)!<BR>\n" );
document.write( "Cancel out 6!<BR>\n" );
document.write( "Total number of sets of 4 books = 10*9*8*7/4!<BR>\n" );
document.write( "Total number of sets of 4 books = 10*9*8*7/4*3*2<BR>\n" );
document.write( "Total number of sets of 4 books = 5040/24<BR>\n" );
document.write( "Total number of sets of 4 books = 210\r<BR>\n" );
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document.write( "210 different sets are possible out of 10 books.\r<BR>\n" );
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