Do we have to?
Unfortunately, unit conversion is a way of life.
To provide 48 donuts for your class, how many dozen donuts should you buy?
If the speed limit on I-5 were 100 km/h, would you be able to get to Portland in less time or more time than at the present limit of 70 mph?
Is one brand a better bargain at $3.50/lb or should you buy the competitor at $8.05/kg?
Would you rather mow a lawn that is one hectare or one that is 8 acres?