fun addStrNums( num1: String, num2: String):String { var isNum1 = true var isNum2 = true isNum1 = num1.matches("-?\\d+(\\.\\d+)?".toRegex()) isNum2 = num2.matches("-?\\d+(\\.\\d+)?".toRegex()) if (isNum1 && isNum2){ var n1 = num1.toInt() var n2 = num2.toInt() return "${n1+n2}" } else return "not Number" }