function IsNum(u)
{
   var i = 0;
   RC = true;
   while (RC && (i < u.length ))
   {
      if (! ((u.charAt(i) >= "0" && u.charAt(i) <= "9") || u.charAt(i) == "."))
      { RC=false; }
      i++;
   }
   return RC;
}

function submitIt(form) {
 if(!IsNum(form.earnings.value)) {
   alert("Do not use a comma or dollar sign or other non-numeric characters!")
   form.earnings.focus()
   form.earnings.select()
   return false
 }
 if(!IsNum(form.lastEarn.value)) {
   alert("Do not use a comma or dollar sign or other non-numeric characters!")
   form.lastEarn.focus()
   form.lastEarn.select()
   return false
 }
 if(!IsNum(form.lastYearEarn.value)) {
   alert("Do not use non-numeric characters!")
   form.lastYearEarn.focus()
   form.lastYearEarn.select()
   return false
 }
 if(!IsNum(form.retiremonth.value)) {
   alert("Do not use non-numeric characters!")
   form.retiremonth.focus()
   form.retiremonth.select()
   return false
 }
 if(!IsNum(form.retireyear.value)) {
   alert("Do not use non-numeric characters!")
   form.retireyear.focus()
   form.retireyear.select()
   return false
 }
 return true
}