[ahakki]

Well they're french, so M stands for Mille (one thousand). MM is just a thousand squared, and MMM is a thousand qubed.

Once you understand this system you might also understand why the long system makes more sense.

  1000                 = Mille     M
  1000 000             = Million   MM
  1000 000 000         = Milliard  MM M
  1000 000 000 000     = Billion   MM MM 
  1000 000 000 000 000 = Billiard  MM MM M

in the short system the billion (nine zeros) has nothing to do with two. while in the long system it represents double as many zeros as the million. a trillion has three times the Zeros. -ard suffix? add 3 zeros

[ubernostrum]

As someone who used to speak decent French, you will never convince me that the language is rational with respect to numbers. The sometimes-decimal/sometimes-vigesimal thing still makes my head spin all these years later when I hear numbers being spoken in French.