def grid_score_calc(grid_info, occupancy_rate):
    """take info from single grid square and occupancy_rate, calculate and return that grid's center point theft score. 

    grid_info's format: (num_racks, num_corners, num_thefts)
    >>> grid_info = (5, 2, 10)
    >>> grid_score_calc(grid_info, .5)
    0.5795574288724974
    """
    # variable used to assume one theft and one rack at all locations 
    norm = 1 

    # calculate the approx num of bikes in area over 8 years of data 
    bicycles_in_area_8_years = ((grid_info[0] * 2 + (grid_info[1] + norm)) * 365 * 8) * occupancy_rate 

    # multiply the percentage by 1000 to move results up 3 decimal places
    stolen_bicycle_percentage = (grid_info[2] + norm) / bicycles_in_area_8_years * 1000

    return stolen_bicycle_percentage