Numbers are usually one of the first and most important things you can learn in a foreign language.
They are not simply useful for saying your age, eg ich bin fünfzehn Jahre alt, but can be used for prices, dates, times, distances, weights, measures and many more things.
Germany is directly bordered by nine countries, and only has a coastline in the north (North Sea – die Nordsee – and Baltic Sea – die Ostsee).
Germany's largest ports are Hamburg and Bremen, but there are also important river ports, such as Köln (Cologne) on the River Rhine (Rhein) which has been a busy waterway for centuries.
Austria and Switzerland are landlocked and have no coastline at all, so their only ports are river ports. Birsfelden is an important port in Switzerland near the source of the Rhein.