2207 /www/nrich/html/content/04/weekly/prob11/ 1 2010-08-07T13:24:14 <?xml version="1.0" encoding="UTF-8"?> <mdoxml version="1.0"><br></br> <p>In a magic square, each row, each column and both main diagonals have the same total. In the partially completed magic square shown, what number should replace x?</p> <p>Use the interactivity below:</p> <p style="text-align: center;"><mdo:flash height="141" id="/content/04/weekly/prob11/magic_square.swf" width="141"><param name="allowfullscreen" value="true"></param><param name="fullscreen" value="true"></param> <param name="movie" value="magic_square.swf"></param> <param name="quality" value="high"></param> <param name="bgcolor" value="#FFFFFF"></param> </mdo:flash></p> <p>If you liked this problem, <a href="http://nrich.maths.org/5525">here is an NRICH task</a> which challenges you to use similar mathematical ideas.</p></mdoxml> <?xml version="1.0" encoding="UTF-8"?> <mdoxml version="1.0"> <p>The numbers along the leading diagonal total 58, which is therefore the sum of each row and each column. We can now calculate that the number to the left of 10 must be 20 and below that must be 7. Hence x=21</p> </mdoxml> 2 3 0 0 0 0 0 Weekly Problem 41 - 2011 Information and Communications Technology Interactivities Secondary Mapping Document Equations and formulae LS