
Finger Binary - brudgers
https://en.wikipedia.org/wiki/Finger_binary
======
rawnlq
Someone mentioned a few days ago that they use gray code to count instead
since you only change one finger per increment:

[https://news.ycombinator.com/item?id=10131057](https://news.ycombinator.com/item?id=10131057)

And actual submission:
[https://news.ycombinator.com/item?id=10128815](https://news.ycombinator.com/item?id=10128815)

~~~
mycelium
How do you increment the count as you count? Memorization?

I can count binary. I don't know which bit/finger to flip to count in gray
code.

~~~
osense
Just as there is a pattern to "regular" binary coding, there is a pattern to
the Gray code -- albeit, perhaps, a more complex one. I'd imagine that after
practicing counting from 0 to, say, 15, you'll be able to count further up on
your own.

~~~
saurik
Some of us grew up with the Brain Puzzler.

[http://www.amazon.com/dp/B000BXFN4E](http://www.amazon.com/dp/B000BXFN4E)

------
hliyan
I developed the following method when I was in school:
[https://drive.google.com/file/d/0B8tashgCVLs9QWY1QldFaE1reVE](https://drive.google.com/file/d/0B8tashgCVLs9QWY1QldFaE1reVE)

(notice that extended fingers indicate 0, not 1)

------
kazinator
There is binary code, and of course you can represent it with fingers. Nobody
does this, though. That is to say, there is no cultural practice of "finger
binary". Finger binary is not a "thing" that's "out there". Whoever wrote this
Wikipedia page just made it up. The Wikipedia must document the existence of
real things that are out there, and can be properly referenced.

Should there be a Jelly Bean Binary wikipedia page, just because you can use
jelly beans of two colors to represent binary? How about Othello Binary? Using
the two-colored chips from the disc-flipping game for counting in binary?

~~~
AnkhMorporkian
I was taught this method of counting by my dad when I was 6 or 7 years old; so
it's been around for at least a couple decades.

------
micaeked
I find using the thumb for the first digit much better, since it's the one
switching each time when counting up or down. I use this for counting down
reps on one hand and sets on the other during exercise.

~~~
dllthomas
Yeah, that's how I've always done it, too.

------
timharding
Nerdiest gang signs ever.

~~~
dexterdog
I would definitely join the 16 gang

------
hiq
Does anybody have an interesting use case for this? Just curious whether it's
actually used.

~~~
asciimo
I always thought, "how high can you count using your fingers" would be a fun
interview question.

~~~
logicallee
Oooooh, I love "guess what the interviewer is thinking instead of answering
his question."

For example the natural response might be, "Well, I personally can count to
ten" and, after you pressed about alternative schemes: "On a more theoretical
level you could of course enumerate way more states than ten using your
fingers. Just think of American sign language, which has 26 letters only one
of which includes motion (the Z).[1] And that's on a single hand, so just
counting the letters in ASL only - and no other gestures, you can count to at
least 676. Add a few more static hand shapes - there are lots of shapes in
ASL- maybe try to learn a hundred per hand, which is good because you can
encode two digits in each hand, I could confidently count to 10,000 using just
my fingers. It would probably take no more than a few days to learn."

Would I pass your interview? Probably not, because it wasn't what you were
thinking of. Even though I just showed you that I could count to ten times
higher than the number you were thinking of.

And I wouldn't even mention what I was REALLY thinking which is "Hmmmm, I
wonder where the limit is. A human hand has about 26 degrees of freedom, so
two hands have about 52, if we encode a degree using just 2 bits - one of four
levels of flexion - we're at 52 * 2 = 104 bits. So something like 10^31 = what
is that 'ten nonillion'. I probably shouldn't say nonillion. No, I definitely
shouldn't say nonillion. Probably even a million is pushing it, I shouldn't
say that. But I bet it's possible - a million is just twenty bits, that's just
10 bits per hand, or two bits per finger and it's obvious that a finger has
way more than 4 positions it can take - looking at my own hand my first
knuckles are independent of the crook of the finger, it doesn't take much
effort at all to control them independently.... I bet I can count to a
million."

[1] [http://www.lifeprint.com/asl101/pages-
layout/handshapes.htm](http://www.lifeprint.com/asl101/pages-
layout/handshapes.htm)

~~~
technomancy
Maybe you wouldn't get the job not because you gave a different answer, but
because you assumed the worst about the interviewer; that he was a fool who
didn't know how to run an interview.

~~~
moron4hire
To be fair, that is often a good assumption to make.

------
regehr
My kids enjoy finger binary since they only need to count to four in order to
give me the finger.

~~~
wiredfool
Yeah. I just have to laugh when the 5 yr old says, "It's not rude, it's a
binary 4". The things kids pick up...

------
Xophmeister
Ah, misspent youth!... I remember having completions with my friends, at 17,
to see who could cycle through all 1024 states the fastest. AFAIK, I'm still
the record holder at just over six minutes. I'm 33 now, with no sign of
arthritis ;)

------
pliny
18 is conspicuously missing, is anyone (everyone?) incapable of extending both
their thumb and their ring finger? Or extending their ring finger alone,
without using their thumb to hold down the middle finger?

~~~
gamegoblin
I came here to ask this same question.

On my right hand, I can move my ring finger as independently as any other, but
on my left hand, I cannot extend it fully by itself. I can extend it if I
simultaneously extend the adjacent pinky, but not alone.

~~~
omegaham
Interesting - I can't do it with either hand. If I bring my ring finger out,
the pinky comes out too unless it's held in place by my thumb.

------
njloof
I learned this as a kid -- I think from a program in Cursor Magazine
(distributed on cassette tape!) for the Commodore Pet. You can only count to
99, but it's a little more practical for base 10 calculation:

[https://en.wikipedia.org/wiki/Chisanbop](https://en.wikipedia.org/wiki/Chisanbop)

------
hackuser
I suspect the following has been posted on HN many, many times, but I haven't
seen it:

Finger hex is much simpler, though you can't count as high (2^5):

* Your thumb is the pointer

* Your other 4 fingers have 4 joints each

You can figure it out from there. That's 2^4 on each hand. You also could do
the alphabet, with a few code joints[1] left over.

[1] Sorry, couldn't resist

------
PhineasRex
While you can count very high using this method, it's quite difficult to make
some of the numbers. I've found the optimal tradeoff to be base-6; using one
hand to keep track of the first position and the other the second position.

------
geetee
Interesting to think about how much more information you can encode in by
using various hand positions (e.g. rotating on different axes.)

~~~
tomadi
Numberphile shows how to sign up to a trillion in one video. (Sign , not count
--- you don't have time to count that high!)

------
JTxt
I do this too, though I find it much easier to tap on a surface than to
extend/contract arbitrary fingers.

------
spike021
Wish I'd learned this when I was younger. This would come in very handy (pun
unintended).

~~~
lozf
I learned this when I was younger. People thought I was weird.

------
spapin
Do you think the numbers given as example are just randomly choosen? 7 (ok
sign) 8 (pointing finger) 11 (should have been 13?) 12 (peace sign) 25
(satan/metal hand sign)

They missed 4 ( _the_ finger) 17 (phone sign)

Coincidence? I don't think so... Aliens, maybe.

