I cant callculate take right tile from my grid

i have some problem.
my script board

Code (CSharp):

1. private GameTile[,] board;
2.     private Vector2 offset;
3.  
4.     [SerializeField] float cellWidth;
5.     [SerializeField] float cellHeight;
6.     [SerializeField] int countX;
7.     [SerializeField] int countY;
8.     [SerializeField] GameObject background;
9.  
10.     private float boardWidth;
11.     private float boardHeight;
12.  
13.     public void CreateBoardCells()
14.     {
15.  
16.         float worldHeightScreen = Camera.main.orthographicSize * 2f;
17.         float worldWidthScreen = worldHeightScreen / Screen.height * Screen.width;
18.  
19.         cellWidth = worldWidthScreen / (countX + 2);
20.         cellHeight = worldHeightScreen / (countY + 6);
21.  
22.         boardWidth = cellWidth * countX;
23.         boardHeight = cellHeight * countY;
24.  
25.         board = new GameTile[countX, countY];
26.  
27.         offset = new Vector2(boardWidth * 0.5f, boardHeight * 0.5f);
28.  
29.         for (int x = 0; x < board.GetLength(0); x++)
30.         {
31.             for (int y = 0; y < board.GetLength(1); y++)
32.             {
33.                 Vector3 position = new Vector3((x * cellWidth + cellWidth / 2) - offset.x,
34.  (y * cellHeight + cellHeight / 2) - offset.y);
35.                 board[x, y] = new board();
36.             }
37.         }
38.     }
39.  

and its created a board game with sprites what i want at center relative from screen
and i try to callculate position from mouse to my grid but every time fail because i am not cool math and suppouse callculate something wrong
script callculate grid

Code (CSharp):

1. public GameTile GetTileFromMap(Vector3 worldPos)
2.     {
3.         float percentegeX = (worldPos.x + boardWidth / 2) / boardWidth;
4.         float percentegeY = (worldPos.y + boardHeight / 2) / boardHeight;
5.         percentegeX = Mathf.Clamp01(percentegeX);
6.         percentegeY = Mathf.Clamp01(percentegeY);
7.         float countValueX = countX - 1;
8.         float countValueY = countY - 1;
9.         int x = Mathf.RoundToInt(countValueX * percentegeX);
10.         int y = Mathf.FloorToInt(countValueY * percentegeY);
11.         return board[x, y];
12.     }

and it almost works as it should, just super inaccurate. for example, if you press on a cell from 0-7, then he will sometimes select it and sometimes not. apparently the surroundings are super inaccurate

 

You may want to check out Unity's Grid class to handle the calculations if math is not your strong suit. (math is not my strong suit, so I can't debug your math)

https://docs.unity3d.com/ScriptReference/Grid.html

You can convert coordinates using CellToWorld and WorldToCell, and then use the Cell coordinates to look up a tile from your board array.