How do I switch from one method to another with switch statement or loop?

So far, I've been able to make the methods and allow for the user to exit immediately. What I've been having trouble with is....

1. Having the user select an operation (add, subtract, multiply, divide)


2. Having a method to choose an operation


3. Then proceeding with the getNumber statement and the different operations

Edit: Thanks dawner for helping with the getNumber, I owe you Here's what I have so far

import java.util.*;
import java.security.*;
public class Project6
{
    public static void main(String[] args)
    {
    boolean Go = true;
    while(Go)
    {
    Scanner input = new Scanner(System.in);
    System.out.println("Choose an operation");
    System.out.println("1 for Addition");
    System.out.println("2 for Subtraction");
    System.out.println("3 for Multiplication");
    System.out.println("4 for Division");
    System.out.println("5 to Quit");
    int response=input.nextInt();
    if(response == 5)
    {
       System.out.print("You have quit the calculator");
       Go = false;
    }
    Operation(response);
    }
}
public static void Operation(int response)
{
    switch(response)
    {
        case 1: add(); break;
        case 2: subtract(); break;
        case 3: multiply(); break;
        case 4: divide(); break;
        default: System.out.println("Invalid Response");
    }
}
public static void getNumber()
{
    try
    {
        SecureRandom num = SecureRandom.getInstance("SHA1PRNG");
        int digit1;
        digit1 = num.nextInt();
        int digit2;
        digit2 = num.nextInt();
    }
    catch(NoSuchAlgorithmException nsae)
    {
        System.out.println("Is SHA1PRNG spelled correctly?");
    }
}
public static void add(int digit1, int digit2)
{
    Scanner input = new Scanner(System.in);
    int sum;
    sum = digit1 + digit2;
    System.out.println("What is " + digit1 + " + " + digit2 + " ?");
    int ans;
    ans = input.nextInt();
    if(ans == sum)
    {
        correctPrompt();
    }
    else
    {
        incorrectPrompt();
    }
}
public static void subtract(int digit1, int digit2)
{
     Scanner input = new Scanner(System.in);
     if(digit2 > digit1)
     {
         int temp = digit1;
         digit1 = digit2;
         digit2 = temp;
     }
     int diff = digit1 - digit2;
     System.out.println("What is " + digit1 + " - " + digit2 + " ?");
     int ans;
     ans = input.nextInt();
     if(ans == diff)
     {
          correctPrompt();
     }
     else
     {
          incorrectPrompt();
     }
}
public static void multiply(int digit1, int digit2)
{
     Scanner input = new Scanner(System.in);
     int product = digit1 * digit2;
     System.out.println("What is " + digit1 + " * " + digit2 + " ?");
     int ans = input.nextInt();
     if(ans == product)
     {
         correctPrompt();
     }
     else
     {
         incorrectPrompt();
     }
}
public static void divide(int digit1, int digit2)
{
    int quotient;
    quotient = digit1 / digit2;
    int remainder = digit1 % digit2;
    if(digit2 > digit1)
    {
        int temp = digit1;
        digit1 = digit2;
        digit2 = temp;
    }
    if(remainder == 0)
    {
        Scanner input = new Scanner(System.in);
        System.out.println("What is " + digit1 + " / " + digit2 + " ?");
        int ans = input.nextInt();
        System.out.println("What is the remainder?");
        int remainAns = input.nextInt();
        if(ans == quotient && remainAns == remainder)
        {
            correctPrompt();
        }
        else
        {
            incorrectPrompt();
        }
    }
    else
    {
        Scanner input = new Scanner(System.in);
        System.out.println("What is " + digit1 + " / " + digit2 + " ?");
        int ans;
        ans = input.nextInt();
        if(ans == quotient)
        {
            correctPrompt();
        }
        else
        {
            incorrectPrompt();
        }
    }
}
public static void correctPrompt()
{
    try
    {
        String response;
        response = "";
        SecureRandom num = SecureRandom.getInstance("SHA1PRNG");
        int randResponse;
        randResponse = num.nextInt(4);
        switch(randResponse)
        {
            case 0: response = "Excellent!"; break;
            case 1: response = "Nice Work!"; break;
            case 2: response = "Right - you rock"; break;
            case 3: response = "Well Done"; break;
        }
        System.out.println(response);
    }
    catch (NoSuchAlgorithmException nsae)
    {
        System.out.println("Is SHA1PRNG spelled correctly?");
    }
}
public static void incorrectPrompt()
{
    try
    {
        String response= "";
        SecureRandom num = SecureRandom.getInstance("SHA1PRNG");
        int randResponse;
        randResponse = num.nextInt(4);
        switch(randResponse)
        {
            case 0: response = "No, please try again"; break;
            case 1: response = "Oopsie! You are SO close!"; break;
            case 2: response = "Don't give up - you can do this"; break;
            case 3: response = "Promime no fumigare - Close, but no cigar"; break;
        }
        System.out.println(response);
    }
    catch (NoSuchAlgorithmException nsae)
    {
        System.out.println("Is SHA1PRNG spelled correctly?");
    }
}
}