document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=669969>Question 669969</A>: <I><SPAN STYLE=\"word-break: break-all;\"> Can anyone walk me through how to solve: N=1X2X3X4...X20 how many terminal zeros will N have<BR>\n" );
document.write( "I found a \"solution\" that uses prime number factors, but I do not understand how prime numbers help solve this problem.  Can some one explain this to me? Thank you so much! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #416702 by </B><A HREF=/tutors/aboutme.mpl?userid=josmiceli><B>josmiceli(19441)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=josmiceli><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=josmiceli><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=416702\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> If e means even and o means odd,<BR>\n" );
document.write( "These are some multiplication rules:<BR>\n" );
document.write( "e x e = e<BR>\n" );
document.write( "e x o = e<BR>\n" );
document.write( "o x o = o<BR>\n" );
document.write( "--------<BR>\n" );
document.write( "The first terminal zero appears when you<BR>\n" );
document.write( "multiply<BR>\n" );
document.write( "o x e x o x e x 5 and this is<BR>\n" );
document.write( "e x e x 5<BR>\n" );
document.write( "e x 5<BR>\n" );
document.write( "which gives me a terminal zero. If it was<BR>\n" );
document.write( "o x 5, I would have a terminal 5<BR>\n" );
document.write( "--------------<BR>\n" );
document.write( "Now, continuing, <BR>\n" );
document.write( "e x 0 x e x o x 10<BR>\n" );
document.write( "e x e x 10<BR>\n" );
document.write( "e x 10<BR>\n" );
document.write( "which gives me 2 terminal zeros so far<BR>\n" );
document.write( "----------------------------<BR>\n" );
document.write( "o x e x o x e x 15<BR>\n" );
document.write( "e x e x 15<BR>\n" );
document.write( "e x 15<BR>\n" );
document.write( "which gives another terminal zero, 3 so far<BR>\n" );
document.write( "---------------<BR>\n" );
document.write( "e x o x e x o x 20<BR>\n" );
document.write( "e x e x 20<BR>\n" );
document.write( "e x 20<BR>\n" );
document.write( "the last terminal zero, 4 total<BR>\n" );
document.write( "You can check on a calculator. Find 20!\r<BR>\n" );
document.write( "<BR>\n" );
document.write( "\n" );
document.write( " </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );