function update_price(n){
 var v;
 if (n == 1){
  v='4.00';
 }else if (n > 1 && n < 26){
  v='3.25';
 }else if (n > 25 && n < 51){
  v='3.00';
 }else{
  v='2.75';
 }

 document.orderform.amount.value=n * v;
 if (n==1){
  document.orderform.no_shipping.value='1';
  document.orderform.item_name.value='The Updated Herpes Handbook- 1 copy ';
  $('calc_price').innerHTML= '$'+document.orderform.amount.value + ' (includes postage)';
 }else{
  document.orderform.no_shipping.value='2';
  document.orderform.item_name.value='The Updated Herpes Handbook- ' + n +' copies ';
  $('calc_price').innerHTML= '$'+document.orderform.amount.value + ' ($' + v + ' each plus 15% postage)';
 }
 return 0;
}