Help with Percentage

Hi,

I'm new user of acrobat 9.

I'm trying to calcalute a percentage and I'm having problems with calculation script
var c = Number(this.getField("P3").value);
var d = Number(this.getField("P4").value);
var T2=(d/c)*100;
if(c < 1 || isNaN(T2))
event.value = 0;
else
event.value = T2;

When I put format on T2 as "Number" in properties if I insert P3=10 and P4=10 I get the result 100.00 and if I change de format to "percentage it shows 10,000.00%.

Please help
Kind Regards
Lubu