Generate several random numbers, one of which must be the correct answer to a sum? - random

Question

I have created a Space Invaders game in which the player must shoot an asteroid which displays a random number. A sum will also be randomly generated at the start of the scene. Once the player shoots an asteroid the scene reloads, with points awarded for correct answers.
The problem I am having is that I need at least one asteroid to display the correct answer. I am currently achieving this by reloading the scene until an asteroids number matches the answer to the sum. This can take quite a few reloads and looks really bad. Is there a better way to achive this which will look better and be more efficient. I have included my effort below. I appreciate any comments. Thanks!
Script for checking the correct answer and reloading the scene.
#pragma strict
function Start ()
{
}
{
if (
Asteroid1_Script.asteroid1Value != (Sum_Script.sumA - Sum_Script.sumB) &&
Asteroid2_Script.asteroid2Value != (Sum_Script.sumA - Sum_Script.sumB) &&
Asteroid3_Script.asteroid3Value != (Sum_Script.sumA - Sum_Script.sumB) &&
Asteroid4_Script.asteroid4Value != (Sum_Script.sumA - Sum_Script.sumB) &&
Asteroid5_Script.asteroid5Value != (Sum_Script.sumA - Sum_Script.sumB)
)
{
Application.LoadLevel("L1");
}
}
Script for randomly generating the sum.
#pragma strict
static var sumA :int = 0;
static var sumB :int = 0;
function Start ()
{
var newSumA = Random.Range(6,10);
sumA = newSumA;
var newSumB = Random.Range(1,6);
sumB = newSumB;
}
function Update () {
//Question Output.
guiText.text = sumA.ToString() + " - " + sumB.ToString()+ " =";
}
Script for generating an asteroids random number.
#pragma strict
var mainCam: Camera;
static var asteroid1Value : int = 0;
var asteroid1 : Transform;
var Asteroid1Style : GUIStyle;
function Start ()
{
var newAsteroid1Value = Random.Range(0,10);
asteroid1Value = newAsteroid1Value;
asteroid1.position.x = mainCam.ScreenToWorldPoint (new Vector3 (160f, 0f, 0f)).x;
asteroid1.position.y = mainCam.ScreenToWorldPoint (new Vector3 (0f, 450f, 0f)).y;
}
function OnGUI()
{
var point = Camera.main.WorldToScreenPoint(transform.position);
GUI.Label(new Rect(point.x, Screen.currentResolution.height - point.y - 530, 110, 100), asteroid1Value.ToString(), Asteroid1Style);
}
function OnCollisionEnter(col : Collision)
{
if(asteroid1Value == (Sum_Script.sumA - Sum_Script.sumB))
{
Destroy(gameObject);
Score_Script.score ++;
}
if(asteroid1Value != (Sum_Script.sumA - Sum_Script.sumB))
{
Score_Script.score --;
}
}

Answer 1

Do as you are doing, generate 5 random numbers for your asteroids.
Then generate a random number between 1 and 5, this is your random asteroid, and then set its value to the answer. (sumA - sumB)

Answer 2

You just need to abstract your logic.
The best argument I can make is, simply put, build your random numbers before you build your asteroids.
That way, you always have a correct one.
I would simply code:
function start(){
var x = 5 //X being whatever number of asteroids you wish.
var a = new Array();
for(var i=0; i<x; i++){
a[i] = Random.Range(0,10);
}
for( i in a){ buildAsteroid(a[i]) }
}
And... if the number matches, success.