Why aren't these numbers going down by 1.

Hey. So I got this script to show stamina in my game. It’s in C# and I’m not good at it. If found it at a forum and added some bits to it to fit me. One of which is displaying the stamina, at the bottom in GUI. The problem I have is that when I start running the number goes down by decimals and not whole numbers so the whole thing looks weird on screen. How do I make it so it simply goes down 1 by 1 and not in decimals.

using UnityEngine;
using System.Collections;

public class StaminaRun : MonoBehaviour
{
	private float barLength = 0.0f;
	
    // Max running time
    public float RunningTime = 10f;

    // How fast do we regenerate available running time?
    public float RestRate = 1f;

    // Player must be able to run for at least X seconds
    public float RunThreshold = 2f;

    private vp_FPPlayerEventHandler Player;
    public float availableRunTime;

    protected virtual void Awake()
    {

        // cache the player event handler
        Player = GameObject.FindObjectOfType(typeof(vp_FPPlayerEventHandler)) as vp_FPPlayerEventHandler;
        availableRunTime = RunningTime;

    }

    /// <summary>
    /// registers this component with the event handler (if any)
    /// </summary>
    protected virtual void OnEnable()
    {

        // allow this monobehaviour to talk to the player event handler
        if (Player != null)
            Player.Register(this);

    }

    /// <summary>
    /// unregisters this component from the event handler (if any)
    /// </summary>
    protected virtual void OnDisable()
    {

        // unregister this monobehaviour from the player event handler
        if (Player != null)
            Player.Unregister(this);

    }

    public void Update()
    {
        if (!Player.Run.Active)
        {
            // If we're not running, regenerate our stamina
            availableRunTime = Mathf.Min(availableRunTime + Time.deltaTime * RestRate, RunningTime);
            return;
        }

        // Decrease our running time available and see if we have to stop
        availableRunTime -= Time.deltaTime;
        if (availableRunTime <= 0)
        {
            Player.Run.TryStop();
            availableRunTime = 0;
        }
    }

    protected virtual bool CanStart_Run()
    {
        // Only enable running if we're above the running threshold
        if (availableRunTime >= RunThreshold)
            return true;

        return false;
    }
	
	void  OnGUI ()
	{

	GUI.Box(new Rect(5, 130, 55, 23), "Stamina");
		
	GUI.Box(new Rect(62, 130, barLength, 23), availableRunTime + "/" + 10);
	
	}
	
	void  Start ()
	{
		barLength = Screen.width / 7;
	}

}

This is because Time.deltaTime is a float. Try using Mathf.FloorToInt() to calculate it as an int, which is a whole number.