This is the code for the Calculator:

package main

import (
    "fmt"
    "math"
)

func main() {

    var num1, num2 float64
    var operator string

    fmt.Println("Welcome to the calculator")

    fmt.Print("Enter your first number : ")
    fmt.Scanln(&num1)

    fmt.Print("Enter your operator '+, -, *, /, %, ^' : ")
    fmt.Scanln(&operator)

    fmt.Print("Enter your second number : ")
    fmt.Scanln(&num2)

    result := calculate(num1, num2, operator)

    fmt.Printf("Result : %f %s %f = %f\n", num1, operator, num2, result)
    fmt.Println("Thank You for using the calculator :)")
}

func calculate(num1, num2 float64, operator string) float64 {

    var result float64

    switch operator {
        case "+":
            result = num1 + num2
        case "-":
            result = num1 - num2
        case "*":
            result = num1 * num2
        case "%":
            result = (num1 / num2) * 100
        case "^":
            result = math.Pow(num1, num2)
        case "/":
            if num2 != 0 {
                result = num1 / num2
            } else {
                fmt.Println("Divide by Zero '0' error!")
            }
        default:
            fmt.Println("Invalid operator!")
    }

    return result
}

You can run this code by using:
"go run your_file_name.go"