How to save billions of dollars.

[Zenda]

The metric system is not limited to 7 base units. It doesn't say you can't use your own convenient units. It only requires you to define such units in SI units. That's why solar mass and atomic mass units are so popular around the world, and noone needs to guess how much it actually is.

If that's all it takes: 1 foot = 0.3048 meters. So now can America keep using feet? Same goes for pounds and everything else.

The reason to use solar masses and atomic masses is that expressing values in SI units would give unwieldy numbers (too many zeros, like Pete said). There is no such argument for feet, miles or pounds. There are only unnecessary calculations in communications, which leave room for unneeded mistakes.