By which rule of thumb can you determine the braking distance in metres from speed when braking normally?

You answered correctly. In Germany, the rule of thumb to estimate the normal braking distance (in meters) is: divide your speed in km/h by 10, then square that result. For example, at 50 km/h: (50/10) = 5, then 5 x 5 = 25 meters. This quick formula helps you gauge how much distance you will need to stop under normal braking conditions. Remember, this is only for normal braking—not for emergency stops, which require a different calculation. This rule helps drivers keep enough distance and anticipate stopping needs in everyday traffic.