i am coding a site that returns info from zillow in xml format i need to do a calculation against the sqft of the yard the problem is when i parse the xml i think i am getting a string i cannot convert it to a number here is a sample of the xml

<?xml version="1.0" encoding="utf-8" ?>
<SearchResults:searchresults xmlns:SearchResults="http://www.zillow.com/vstatic/3/static/xsd/SearchResults.xsd">
<request>
<address>2114 Bigelow Ave</address>
<citystatezip>Seattle, WA</citystatezip>
</request>
<message>
<text>Request successfully processed</text>
<code>0</code>
</message>
<response>
<results>
<result>
<zpid>48749425</zpid>
<links>
<homedetails>http://www.zillow.com/HomeDetails.htm?city=SEATTLE+&state=WA&zprop=48749425&partner=<ZWSID></homedetails>
<graphsanddata>http://www.zillow.com/Charts.htm?chartDuration=1year&zpid=48749425&cbt=7539332184936698527%7E6%7EQfx6yogHrAI8nbK0h08BMT90x4V8jO7i8n7y%2BzmUaQU%3D&partner=<ZWSID></graphsanddata>
<mapthishome>http://www.zillow.com/search/Search.htm?mode=search&zpid=48749425&partner=<ZWSID></mapthishome>
<myestimator deprecated="true">http://www.zillow.com/myzestimator/MyZestimatorHomeFactsPage.htm?context=1157752261267&zprop=48749425&partner=<ZWSID></myestimator>
<myzestimator deprecated="true">http://www.zillow.com/myzestimator/MyZestimatorHomeFactsPage.htm?context=1157752261267&zprop=48749425&partner=<ZWSID></myzestimator>
</links>
<address>
<street>2114 Bigelow Ave N</street>
<zipcode>98109</zipcode>
<city>SEATTLE</city>
<state>WA</state>
<latitude>47.637934</latitude>
<longitude>-122.347936</longitude>
</address>
<zestimate>
<amount currency="USD">1124072</amount>
<last-updated>09/01/2006</last-updated>
<oneWeekChange currency="USD">25563</oneWeekChange>
<valuationRange>
<low currency="USD">966702</low>
<high currency="USD">1236479</high>
</valuationRange>
<percentile />
</zestimate>
</result>
</results>
</response>
</SearchResults:searchresults>
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