The prefix was a part of the original metric system in 1795. It is not in very common usage, although the deca pascal is occasionally used by audiologists . The deca newton is also encountered occasionally, probably because it is an SI approximation of the kilogram-force . Its use is more common in Central Europe . In German, Polish, Czech, Slovak and Hungarian, deka (or deko ) is common and used as a word on its own, always meaning decagram . A runway number typically indicates its magnetic azimuth in decadegrees .