The metric system wasn't all good

One second is 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom. ... not base 10, but reasonably close to 10 billion. To make metric, one second would only have to be ~8.7% longer. Meaning a metric minute is ~ 54.73 seconds... unless we adjust it too.