document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1173561>Question 1173561</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Suppose apples are in the shape of a pyramid. On the top layer, there is 1 apple. On the second layer, there are 1+2 apples. On the third layer, there is 1+2+3 apples. On the fourth layer, there 1+2+3+4 apples. If there are N number of layers, how many apples are there in total? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #798800 by </B><A HREF=/tutors/aboutme.mpl?userid=Boreal><B>Boreal(15235)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Boreal><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=Boreal><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=798800\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The formula for this is N(N+1)/2. \r<BR>\n" );
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document.write( "there are a variety of ways to show this. I look at the average of all the numbers and multiply by n.<BR>\n" );
document.write( "The average is (1/2)(n+1), and that is multiplied by n.<BR>\n" );
document.write( "The proof came to me looking at lane markers on a track course. </SPAN>\n" );
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