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Comment by simonklitj | Hacker News Reader

In moving from EU to the US, the biggest difference I noticed is the reliance on fractions over decimals. 1/4th of something as opposed to .25. That’s probably what I miss the most about using the metric system on a daily basis.

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A foot being 12 inches makes fractions work really well in US units (as well as a mile being 8 x 10 x 11 x 6 foot). And with it working so well, many people don't seem to be able to imagine to work without them.

In metric a meter isn't as nicely divisible. Of course we get around that by subdividing 1.2m or 1.5m instead (or 0.8, kitchens and lots of furniture is designed in outer dimensions that are fractions and multiplies of 0.8 meters). But that only works well if you write them out add decimals, because saying "this cupboard is 1/2 0.8 meter wide" is just silly

The metre is not used for everything. The standard for construction and manufacturing is the millimetre. In the UK a standard kitchen unit is a 600(mm), with 300 and 900 varients. Appliances come in 500, 600 and 900 widths, that being the gap or unit they (should!) fit into. It would feel unatural to me to say 0.6 etc for a unit. These common dimensions are used like nouns, "You need 3, 600s" rather than "You need 3 units 600mm wide" tying them more closely to language and perhaps then harder to change.

Using fractions sounds great, I think fractions have a human quality and are a more natural way to approach numbers. In writing, I think putting down 0.5 is slightly jarring compared to the better ½, at least in non-technical contexts.

I think this is also a case of just being more familiar with something, I find "1/2" or "3/8" much harder to parse than "0.5" or "0.375" (having grown up in the EU).

Totally agree. And how does it work when you measure a thing and it is 1,35 inch do you in the US convert it to fractions? And how then do you find this fraction?

A ruler sold in the US (and Britain, on the reverse/bottom) has inch markings with fractions.

│.╷.|.╷.│.╷.|.╷.│.╷.|.╷.│.╷.|.╷.│

0⅛¼⅜½⅝¾⅞1

So the measurement, when taken, is 1⅜".

I've seen inch rulers with different fractions, e.g. one end might be eights, the other sixteenths, turn it over and there are tenths.

(I don't know how this works with digital measuring devices — I grew up in Britain so have never used inches professionally. Only in Warhammer and TV screens.)

With digital devices I assume there is a mode switch like in the digital scales I have at home in the US. I actually work in grams for things like bread making which seems easier than a combination of pounds and ounces.

I think I want my writing to reflect how I talk or think about it. So if the spoken sentence is "specification is a half millimetre" then write with ½ instead of "0.5" because the former will be read out correctly.

But that’s my point! The way you talk or think about it is absolutely influenced by what you’re used to, and what you’ve grown up with.

To you, it’s obvious and natural that „half” is 1/2.

To me, it looks off and I have to „convert” it in my mind to 0.5, which is the way I think about it.

Exactly this. A “half” in my mind translates to 0.5. I don’t do any conversion, 0.5 exists as the very concept of “half” in my brain.

One classic trick to estimate a proportion is to do it as a fraction. It might be hard to tell that someone ate 44 % of a pizza, but significantly easier to judge that they ate a quarter and three quarters of the next quarter (which is 7/16 which is 44 %.)

That said, as soon as I need to do any arithmetic on the number (including compare it to other numbers) I convert it from fraction to decimal.

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