document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1102223>Question 1102223</A>: <I><SPAN STYLE=\"word-break: break-all;\"> What is the sum of all natural numbers between 1 and 200 which are multiples of 5? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #716866 by </B><A HREF=/tutors/aboutme.mpl?userid=htmentor><B>htmentor(1343)</B></A><img src=\"/images/stars/stars-12.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=htmentor><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=htmentor><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=716866\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> The multiples of 5 between 1 and 200 are 5, 10, 15, ..., 200<BR>\n" );
document.write( "This forms an arithmetic sequence with first term equal to 5 and common difference equal to 5.<BR>\n" );
document.write( "The nth term is written a_n = 5 + (n-1)*5 = 5n<BR>\n" );
document.write( "The sum of the 1st n terms of an arithmetic sequence is S_n = (n/2)(a + a_n),<BR>\n" );
document.write( "where a = the 1st term<BR>\n" );
document.write( "The last term is 200, so n = 200/5 = 40<BR>\n" );
document.write( "S_40 = 20*(5 + 200) = 4100 </SPAN>\n" );
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