var i = 0; // interest

var m = 0; // months

var f = 0; // factor

var den = 0; 

var s = "0"; // string

var d = 0; // decimal place

function CalcA() {

if(document.calform.interest.value=="" || document.calform.months.value=="" || document.calform.payment.value=="") {

alert("Please fill in all of the required fields.");

}

else { 

if(document.calform.period.options[1].selected == true) {

m = document.calform.months.value * 12;

}

else {

m = document.calform.months.value;

} 

i = Math.pow(((document.calform.interest.value/100)+1),.0833333)-1;

den = i / (i+1);

f = Math.pow((i+1),m)-1;

f /= den;

f *= document.calform.payment.value;

d = String(f).indexOf(".");

s = String(f).substring(0,(d+3));

document.calform.total.value = + s;  

   }

}