         i = i/12
         print(i)
         
+        // calculate data
         let first = (1+i)**n
         let second = first * i
         let third = p * second

        
        print(fith)
        
        resultLabel.text = "\(fith)"
        
    }

    // calculate payment on tap of calculate button
    @IBAction func calculateButtonAction(sender: AnyObject) {
        
        // Set vars to grab string data from input, then convert to double.
        n = loanTerm
        p = (loanAmountTextField.text as! NSString).doubleValue
        i = (rateTextField.text as! NSString).doubleValue
