Display time in 00:00 format? Now it's decimals

Display a timer in the format 00:00 on the game screen:

while True: # main game loop
        mouseClicked = False

        DISPLAYSURF.fill(BGCOLOR) # drawing the window
        drawBoard(mainBoard, revealedBoxes)

        counting_time = pygame.time.get_ticks() - start_time

        # change milliseconds into minutes, seconds
        counting_seconds = str(counting_time//1000).zfill(2)
        counting_minutes = str(counting_time//60000).zfill(2)

        counting_string = "%s:%s" % (counting_minutes, counting_seconds)

        counting_text = font.render(str(counting_string), 1, (0,0,0))




The code above displays a timer in the format 00:00 on the game screen.