Guess the weight of the cake competition?

At a recent Royals Society conference the exact definition of the kilogram was examined. Currently the standard kilogram is a platinum-iridium alloy cylinder which has been kept in the headquarters of the International Bureau of Weights and Measures (BIPM) in Sèvres, near Paris.

Other SI units are based on Planks constant, Avogadro’s Constant or the number of transitions in a caesium atom

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