@skylar @hazlin Imagine being so hopeless that you don't know precisely that 10°C is coldish, 20°C is warm, 30°C is hot and 40°C is very hot and your mind can only fit the concept of two sloppy imprecise cases.

>feet being 12 inches makes them easy to divide cleanly into halves, thirds, quarters, or sixths
Mathematically it is much easier to divide a metric measurement into half's, thirds, quarters or sixths, rather than having to convert it to 25.4mm and then dividing it;
10mm / 2 == 5mm
10mm / 3 == 3.333...mm (don't do this)
10mm / 4 == 2.5mm
10mm / 6 == 1.6666666...mm (don't do this)

1in / 2 == 12.7 mm
1in / 3 == 8.4666666...mm
1in / 4 == 6.35mm
1in / 6 == 4.2333333...mm

If you really want, you can choose 12mm or 12cm as the base measurement as a laugh.