public boolean placeNumber(int row,int col, int val) {
		
		if(checkRow(row,val) && checkColumn(col,val) && checkSquare(row,col,val))
		{
			if(b[row][col] == 0)
				this.filledFields++;
			
			b[row][col] = val;
			return true;
		}
		
		return false;
	}