MG meaning in Maths ?

Metre-gauge railways are narrow-gauge railways with track gauge of 1,000 mm (3 ft 3+3⁄8 in) or 1 metre.

The metre gauge is used in around 95,000 kilometres (59,000 mi) of tracks around the world. It was used by European colonial powers, such as the French, British and German Empires. In Europe, large metre-gauge networks remain in use in Switzerland, northern Spain and many European towns with urban trams, but most metre-gauge local railways in France, Germany and Belgium closed down in the mid-20th century. With the revival of urban rail transport, metre-gauge light metros were established in some cities, and in other cities, metre gauge was replaced by standard gauge. The slightly-wider 1,009 mm (3 ft 3+23⁄32 in) gauge is used in Sofia.