Question

I have been trying to use a formula that is used to work out exclusive VAT in a program that our team is creating. The formula works correctly when used in a calculator or in excel, though gives a different output when used within a function in our program!

here is the function:

function fn_calcVat()  {     var vRate = Ext.getCmp('crd_vat_rate').getValue();     var vTranAmt = Ext.getCmp('crd_tran_amt').getValue();      if (vRate != '' && vTranAmt != '')      {         alert(Ext.getCmp('vatable').getValue().toString());         var vAmt = 0;         if (Ext.getCmp('vatable').getValue().toString() == 'Y')         {             vAmt = (vRate / ((vTranAmt / 100) + 1));             Ext.getCmp('crd_vat_amt').setValue(vAmt.toFixed(2));             Ext.getCmp('crd_tran_tot').setValue(vTranAmt.toString());             vAmt = 0;         }         else          {             vAmt = ((vRate / 100) * vTranAmt);             Ext.getCmp('crd_vat_amt').setValue(vAmt.toFixed(2));             Ext.getCmp('crd_tran_tot').setValue((vTranAmt + vAmt));             vAmt = 0;         }                     } } 

the problem formula is vAmt = (vRate / ((vTranAmt / 100) + 1));

The other formula is working perfectly.

an example input would be 100 with a VAT rate of 14.00, and the expected answer would be a tax amount of 14, though it gives it as 7!!!

We are using a mashup of EXTJS, js and C#…

Any help would be greatly appreciated.

Kind Regards

Nick

Answer 1

The formula is incorrect, it should be

vAmt = vTranAmt * (vRate / 100.0d);