document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=585046>Question 585046</A>: <I><SPAN STYLE=\"word-break: break-all;\"> ther were 20 people in the house each shake one another. how many hand shakes took place </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #373050 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><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/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=373050\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> ther were 20 people in the house each shake one another. how many hand shakes took place<BR>\n" );
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document.write( "Procedure: Try it with small numbers.<BR>\n" );
document.write( "2 people: 1<BR>\n" );
document.write( "3 people: 2+1 = 3<BR>\n" );
document.write( "4 people: 3+2+1 = 6<BR>\n" );
document.write( "5 people: 4+3+2+1 = 10<BR>\n" );
document.write( "6 people: 15<BR>\n" );
document.write( "----<BR>\n" );
document.write( "20 people: 19+18+...+1<BR>\n" );
document.write( "Sum = (n/2)(a+n) = (19/2)(1+19) = 190<BR>\n" );
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document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
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