@skylar @hazlin I didn't do any conversion, I rather skipped the conversion part and directly used the definition of the inch, which is defined to be 25.4mm.

Playing silly games with fractions like ½, ⅓, ¼, ⅕, ⅙ is pure retardation, as adding them together is a pain in the ass - first you need to convert them to decimal, then you need to add them, then you need to convert them back, which is worse than using decimals and rounding to 0.5mm or .25mm or .75mm or whatever, while maintaining acceptable accuracy.

There is more countries in the world than just the USA and Europe.