8 ms·

Not everyone calculates all the dimensions of what they're building in advance. Sure it's only convenient when you have integer feet divided by multiples of 2,3

by knolax 6y ago

Not everyone calculates all the dimensions of what they're building in advance. Sure it's only convenient when you have integer feet divided by multiples of 2,3 or 4, but those are the first three primes so they're going to be common in a lot of operations. In which case the head math becomes: 4 feet divided by 3 = 4 * 4 inches = 16 inches (It's perfectly reasonable to stop here, your tape measure isn't going only say 1'4") = 16/12 feet + 16%12 inches = 1'4" vs. 4 meters divided by 3 = 4/3meters + ... = 1meter + 4%3/0.3 decimeters = 1.3meter + 4%0.3/0.03 centimeters = 1.33meters ... For each level of precision in metric you have to remember one additional digit, where as in the degenerate case for imperial you remember a constant number of digits at each step. Think of it as making multiples of the {1,1,2}th primes more convenient vs making the {1,3}th primes more convenient.

lopmotr 6y ago
OK. I didn't realize that trick where you multiplied by 4 there. So it works when you're starting with any integer number of feet if you do a little multiplying. But I still doubt this has any practical use. Can you give me a concrete example where you or anybody you know has done this? How common is it?
- knolax 6y ago
  I want to build a shed, I approximate human height as 7 feet because it's a nice even number. I want some number of beams equally spaced nailed onto the posts, I choose 4 posts because 3 and 4 are numbers people default to. 4 beams mean 3 spaces, 7/3=7x4 = 28inches. I nail the beams on every 28 inches. Can we agree that equally spacing 4 of something is a common operation? The metric example would be, 2 meters, divided by 3 = 0.333x2m = 0.666m But look at your tape measure and see which measurement is marked more promimently, an arbitrary centimeter precision measurement or an integer number of inches.
Symbiote 6y ago
4 feet is very nearly 120cm, an equally likely (or approximate) measurement. A third of that is 40cm. Which was supposed to be easier? 30cm divides as well as 12in, and things that aren't nice numbers are easier to handle in cm or mm. Mark out every 4⅝ inches until you have a yard, then mark out every 12mm.
- knolax 6y ago
  Most materials are sold in integer quantities of whatever the unit of measure is.

by knolax 6y ago

lopmotr 6y ago

OK. I didn't realize that trick where you multiplied by 4 there. So it works when you're starting with any integer number of feet if you do a little multiplying. But I still doubt this has any practical use. Can you give me a concrete example where you or anybody you know has done this? How common is it?

knolax 6y ago
I want to build a shed, I approximate human height as 7 feet because it's a nice even number. I want some number of beams equally spaced nailed onto the posts, I choose 4 posts because 3 and 4 are numbers people default to. 4 beams mean 3 spaces, 7/3=7x4 = 28inches. I nail the beams on every 28 inches. Can we agree that equally spacing 4 of something is a common operation? The metric example would be, 2 meters, divided by 3 = 0.333x2m = 0.666m But look at your tape measure and see which measurement is marked more promimently, an arbitrary centimeter precision measurement or an integer number of inches.

Symbiote 6y ago

4 feet is very nearly 120cm, an equally likely (or approximate) measurement. A third of that is 40cm. Which was supposed to be easier? 30cm divides as well as 12in, and things that aren't nice numbers are easier to handle in cm or mm. Mark out every 4⅝ inches until you have a yard, then mark out every 12mm.

knolax 6y ago
Most materials are sold in integer quantities of whatever the unit of measure is.