         if userIsInTheMiddleOfTyping {
             guard let textCurrentlyInDisplay = display.text else { return }
             
-            if digit == "." && (textCurrentlyInDisplay.range(of: ".") != nil) {
+            if digit == "." && (textCurrentlyInDisplay.range(of: Constants.decimalPoint) != nil) {
                 return
             } else {
                 let tmp = textCurrentlyInDisplay + digit
-                display.text = tmp.setMaxLength(of: 8)
+                display.text = tmp.setMaxLength(of: Constants.maxStringLength)
             }
             
         } else {
-            if digit == "." {
-                display.text = "0."
+            if digit == Constants.decimalPoint {
+                display.text = Constants.pointAfterZero
             } else {
                 display.text = digit
             }

    
    private var displayValue: Double {
        get {
            return Double(display.text ?? "") ?? Double.nan
        }
        set {
            let tmp = String(newValue).removeAfterPointIfZero()

    }
}

extension ViewController {
    struct Constants {
        static let cornerRadius: CGFloat = 35.0
        static let decimalPoint: String = "."
        static let emptyString: String = ""
        static let maxStringLength: Int = 8
        static let pointAfterZero: String = "0."
    }
}
