# What is one advantage of the metric system as compared with the U.S. customary system of measurement?

Well, Newton's 2nd law of motion says $F = m a$..........
If inappropriate units are used, i.e. $\text{pounds, shillings, and pence}$, we have to modify the given equation, Newton's famous 2nd law, to give $F = k m a$, where $k$ is some unspecified constant of proportionality.
Actually, Newton originally said $\text{the rate of change of momentum}$ $\text{with respect to time is proportional to the force applied, and in}$ $\text{the same direction......}$ Thus he knew he had to introduce a constant of proportionality.