Passing numbers to Grails taglibs

Passing numbers to Grails taglibs

My test case looks like:
void testFormattedDiv() {
String template = """<itld:formattedDiv numerator="1" denominator="1"
format="###,###" nullNotifier="-"/>"""
String output = applyTemplate(template)
assertEquals "0", output
}
My taglib code starts off with:
def formattedDiv = {attrs, body ->
Number numerator = attrs.get('numerator') as Number
Number denominator = attrs.get('denominator') as Number
However, I get a number format error.
Cannot cast object '1' with class 'java.lang.String' to class
'java.lang.Number'
What is the correct way to pass the number?