8678 /www/nrich/html/content/id/8678/ 1 2011-02-01T00:00:01 <?xml version="1.0" encoding="UTF-8"?> <mdoxml version="1.0"> <br></br> The product of Mary's age in years on her last birthday and her age now in complete months is 1800.<br></br> <br></br> How old was Mary on her last birthday?<br></br> <br></br> If you liked this problem, <a href="http://nrich.maths.org/public/viewer.php?obj_id=4903&amp;part=index&amp;refpage=monthindex.php">here is an NRICH task</a> which challenges you to use similar mathematical ideas.  <br></br> </mdoxml> <?xml version="1.0" encoding="UTF-8"?> <mdoxml version="1.0">Mary was 12 on her last birthday. <br></br><br></br>We need to express 1800 as the product of two factors, one of which (her age in months) is between twelve and thirteen times the other (her age in complete years). <br></br><br></br>These are 150 and 12 respectively. <br></br><br></br>Mary is now 150 months old, i.e. she was twelve on her last birthday and she is now 12 years 6 months old<br></br><br></br></mdoxml> 2 3 0 0 1 0 0 Weekly Problem 10-2005 Algebra Linear equations