Spawn Objects on Grid - how to define size?

Hey! I want to span some cubes on a Grid. for this iam using this script:

 using UnityEngine;
 using System.Collections;
 
 public class WorldSpawn : MonoBehaviour {
 
     public GameObject block1; 
 
     public int worldSize = 10;
 
     public int worldWidth  = 10;
     public int worldHeight  = 10;
 
     public float spawnSpeed = 0;
 
     void  Start () {
         StartCoroutine(CreateWorld());
     }
 
     IEnumerator CreateWorld () {
         for(int x = 0; x < worldWidth; x++) {
             yield return new WaitForSeconds(spawnSpeed);
 
             for(int z = 0; z < worldHeight; z++) {                
                 yield return new WaitForSeconds(spawnSpeed);
 
                 GameObject block = Instantiate(block1, Vector3.zero, block1.transform.rotation) as GameObject;
                 block.transform.parent = transform;
                 block.transform.localPosition = new Vector3(x, 0, z);
             }
         }
     }
 }

what i want to do now is, only have to define the "worldSize" int and the worldWidth and worldHeight gets calculated automatically based on this value. so for example if i say worldSize= 25 the worldHeight&worldWidth should be 5x5. how can i do this?

another question would be how can i do a non-square? so - same example: if i say worldSize= 25 the worldHeight&worldWidth should be 3x8.333 (so in the last row is only one square). how can i do this?