Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

A mathematician's way of converting miles to kilometers

twitter.com

Post reply on HN
Print view View original

21–30 of 208 posts

Re: A mathematician's way of converting miles to kilometers

#21

Post by yholio »

ghaff wrote: post #14
dEnigma wrote: post #10

Fascinating that the second reply (or second best reply?) is an unreasonably angry response: Who the hell needs all this .. Get lost [angry emoji]

There are a fair number of people who seem to take personal offense that the US (and to some degree the UK) don't use SI for everyday types of things and add it to their laundry list of grievances about the US generally. Never mind the fact that SI is generally used for engineering and other areas where it has legitimate advantages (which miles vs. kilometers doesn't really in day-to-day life).

And there are a fair number of people who seem to take personal offense that SI units exist in any form or fashion, perturbing the natural way of the world.

We can't really know to what category this one belongs to.

Re: A mathematician's way of converting miles to kilometers

#23

Post by greatpatton »

gingabriska wrote: post #6

Triple the initial number, add a zero at the end, now halve the resulting number is good enough for my purpose. Brain is surprisingly good at doubling, tripling and halving operations. And visually added zero is quite easy too.

So 1 mile equals 15km? and then you wonder why all these units conversion and up with probe crashing on mars.

Re: A mathematician's way of converting miles to kilometers

#25

Post by nesadi »

ghaff wrote: post #14
dEnigma wrote: post #10

Fascinating that the second reply (or second best reply?) is an unreasonably angry response: Who the hell needs all this .. Get lost [angry emoji]

There are a fair number of people who seem to take personal offense that the US (and to some degree the UK) don't use SI for everyday types of things and add it to their laundry list of grievances about the US generally. Never mind the fact that SI is generally used for engineering and other areas where it has legitimate advantages (which miles vs. kilometers doesn't really in day-to-day life).

> that SI is generally used for engineering

Except when it isn't? Are you telling me SI is used in engineering everywhere in the US? I've heard too many stories (especially accidents) to believe that in any way.

Re: A mathematician's way of converting miles to kilometers

#26

Post by toolslive »

I've been doing it like that as well for years. Most people you explain it (replace the number with a sum of fibonacci numbers, and for each one, take the next) to come back with "but it becomes less accurate for larger numbers, right?". After you say "hm, no!" there's a pause, and then the penny drops: Golden ratio!

Anyway, I can't remember where I learned it.

Re: A mathematician's way of converting miles to kilometers

#27

Post by sudmh »

yholio wrote: post #21
ghaff wrote: post #14

Earlier quoted context omitted.

There are a fair number of people who seem to take personal offense that the US (and to some degree the UK) don't use SI for everyday types of things and add it to their laundry list of grievances about the US generally. Never mind the fact that SI is generally used for engineering and other areas where it has legitimate advantages (which miles vs. kilometers doesn't really in day-to-day life).

And there are a fair number of people who seem to take personal offense that SI units exist in any form or fashion, perturbing the natural way of the world. We can't really know to what category this one belongs to.

The guy seems Indian so he probably belongs to the "confused about existing" category

Re: A mathematician's way of converting miles to kilometers

#28

Post by toolslive »

nesadi wrote: post #25
ghaff wrote: post #14

Earlier quoted context omitted.

There are a fair number of people who seem to take personal offense that the US (and to some degree the UK) don't use SI for everyday types of things and add it to their laundry list of grievances about the US generally. Never mind the fact that SI is generally used for engineering and other areas where it has legitimate advantages (which miles vs. kilometers doesn't really in day-to-day life).

> that SI is generally used for engineering Except when it isn't? Are you telling me SI is used in engineering everywhere in the US? I've heard too many stories (especially accidents) to believe that in any way.

don't they still use pounds per square inch ?

Now, in Europe (excluding the UK) they also still use some weird units from the past. Calories for example, and horse (!!) power.

Re: A mathematician's way of converting miles to kilometers

#29

Post by ghaff »

nesadi wrote: post #25
ghaff wrote: post #14

Earlier quoted context omitted.

There are a fair number of people who seem to take personal offense that the US (and to some degree the UK) don't use SI for everyday types of things and add it to their laundry list of grievances about the US generally. Never mind the fact that SI is generally used for engineering and other areas where it has legitimate advantages (which miles vs. kilometers doesn't really in day-to-day life).

> that SI is generally used for engineering Except when it isn't? Are you telling me SI is used in engineering everywhere in the US? I've heard too many stories (especially accidents) to believe that in any way.

Nope. Hence generally. I haven't made a study of it but I assume Imperial units are more common in civil engineering and other areas that converge with local construction and building trades. Metric is pretty standard in my experience more broadly. (Note also that the better known examples of unit conversion accidents are pretty old as far as I know.)

Re: A mathematician's way of converting miles to kilometers

#30

Post by ghaff »

toolslive wrote: post #28
nesadi wrote: post #25

Earlier quoted context omitted.

> that SI is generally used for engineering Except when it isn't? Are you telling me SI is used in engineering everywhere in the US? I've heard too many stories (especially accidents) to believe that in any way.

don't they still use pounds per square inch ? Now, in Europe (excluding the UK) they also still use some weird units from the past. Calories for example, and horse (!!) power.

PSI is very commonplace though I'm not in a field where I use it in an engineering way. (I actually had to think for a second to come up with the SI equivalent.)

Pounds are one of the real bugbears of imperial in mechanical engineering with lb-f and slugs (i.e. "pounds" conflates mass and weight). Always hated that. I'd convert things to metric and then convert back when I had to work in Imperial.

And I still hear stones from time to time in the UK if you really want archaic.

Post reply on HN