Event.numeric  

// Creates a Label and prints Numeric Key pad is on/off
// depending on the state of the numlock key.
function OnGUI() {
var e : Event = Event.current;
if (e.numeric) {
GUI.Label (Rect (10, 10, 150, 20), "Numeric Key pad is on");
} else {
GUI.Label (Rect (10, 10, 150, 20), "Numeric Key pad is off");
}
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
void OnGUI() {
Event e = Event.current;
if (e.numeric)
GUI.Label(new Rect(10, 10, 150, 20), "Numeric Key pad is on");
else
GUI.Label(new Rect(10, 10, 150, 20), "Numeric Key pad is off");
}
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

def OnGUI():
e as Event = Event.current
if e.numeric:
GUI.Label(Rect(10, 10, 150, 20), 'Numeric Key pad is on')
else:
GUI.Label(Rect(10, 10, 150, 20), 'Numeric Key pad is off')