Cant get keybinding to work

[crowysight]

Hello I am making a game where you chose a range of number then think of a number and then the computer figures out the number you are thinking of. However when I was trying to make It so you could chose the range of numbers I tested It and the keybinding isn’t working and I have tried quite a bit of stuff to make It work but to no avail so some help would be nice.

using UnityEngine;
using System.Collections;

public class Numblywizard : MonoBehaviour {

    // Use this for initialization
    int max;
    int min;
    int guess; 
   
    void Start () {
        StartGame();
    }
   
    void StartGame () {
        min = 1;
        max = 500;
        guess = Random.Range(min,max);
       
        print ("==========================");
        print ("Welcome to Number Wizard!");
        print ("First you must chose the range in which you want me to pick a number");
        print ("Press 1 for 1-100, 2 for 100-1000, 3 for 1-10000, 4 for 1000-10000, 5 for 1-100000, 6 for 10000-100000,7 for 1-1000000, and 8 for 100000-1000000");
       
        if (Input.GetKeyDown(KeyCode.Alpha1)) {
            max = 1000;
            min = 1;
            max = max + 1;
            FirstGuess();
        }else if (Input.GetKeyDown(KeyCode.Alpha2)) {
            max = 1000;
            min = 100;
            max = max + 1;
            FirstGuess();
        }else if (Input.GetKeyDown(KeyCode.Alpha3)) {
            max = 10000;
            min = 1;
            max = max + 1;
            FirstGuess();
        }else if (Input.GetKeyDown(KeyCode.Alpha4)) {
            max = 10000;
            min = 1000;
            max = max + 1;
            FirstGuess();
        }else if (Input.GetKeyDown(KeyCode.Alpha5)) {
            max = 100000;
            min = 1;
            max = max + 1;
            FirstGuess();
        }else if (Input.GetKeyDown(KeyCode.Alpha6)) {
            max = 100000;
            min = 10000;
            max = max + 1;
            FirstGuess();
        }else if (Input.GetKeyDown(KeyCode.Alpha7)) {
            max = 1000000;
            min = 1;
            max = max + 1;
            FirstGuess();
        }else if (Input.GetKeyDown(KeyCode.Alpha8)) {
            max = 1000000;
            min = 100000;
            max = max + 1;
            FirstGuess();
        }       
    }

    void FirstGuess() {
        print ("The highest number you can pick is " + max);
        print ("The lowest number you can pick is " + min);
   
        print ("Is the number higher or lower than " + guess);
        print ("Up arrow = higher, down arrow = lower, Enter = When I have chosen the correct number");
    }
   
    // Update is called once per frame
    void Update () {
        if (Input.GetKeyDown(KeyCode.UpArrow)) {
            min = guess;
            NextGuess();
        }else if (Input.GetKeyDown(KeyCode.DownArrow)) {
            max = guess;
            NextGuess();
        }else if (Input.GetKeyDown(KeyCode.Return)) {
            print("I won!");
            StartGame();
        }
    }
   
    void NextGuess () {
        guess = Random.Range(min,max);
        print ("Higher or lower than " + guess);
        print ("Up arrow = higher, down arrow = lower, Enter = When I have chosen the correct number");
        Update();
    }
}

[gorbit99]

Using code tags properly