Instantiate prefab by total int

If I understand correctly, you want to input a number, and instantiate X number of units? If you want to instantiate say... 50 units.

 void InstantiateMany(int Number, GameObject What2Instantiate, Vector3 Position)
         {
             for (int i = 0; i <= Number ; i++)
             {
                 Instantiate(What2Instantiate, Position, Quaternion.identity);
             }
         }

Then use like:

 InstantiateMany(50, MyPrefab, new Vector3(1f,0f,0f));

That'll spawn 50 MyPrefab's at the location of 1f, 0f, 0f. The issue with this is, they will literally spawn on top of one another. You'll have to do your own logic to spread them out.