How Serious Computer Geeks Count On Their Fingers

February 18, 2016 12:39 PM

How to count to 1000 on two hands Covers counting on your fingers in binary, a skill far more people should have. Be careful you don't offend anyone when you hit 4, 128 and especially 132.

A related Previously

posted by Michele in California (43 comments total)

That would have been a handy trick to learn as a kid. Might have to practice the skill to keep in my pocket as an adult.
posted by verschollen at 12:47 PM on February 18, 2016

you can get even higher (59,000) with finger ternary.
posted by andrewcooke at 12:48 PM on February 18, 2016 [4 favorites]

It's not overly complex, but it's not really all that intuitive either. I'm just not sure what problem this solves; or, why would someone do this, other than because it's kind of neat an abstruse, which is a plus for some people?
posted by clockzero at 12:51 PM on February 18, 2016 [3 favorites]

Sometimes it's useful to be able to count past 10 without taking your shoes off.
posted by McCoy Pauley at 12:52 PM on February 18, 2016 [6 favorites]

I learned it at age 14. It sometimes comes in extremely handy for keeping track of things without any kind of equipment to assist you -- though for large numbers, it can be uncomfortable to hold those positions for extended periods.
posted by Michele in California at 12:53 PM on February 18, 2016

Some interesting stuff on that 3Blue1Brown channel. Thanks.
posted by benito.strauss at 12:56 PM on February 18, 2016 [1 favorite]

There's also this:

On the subject of a measurement system based on twelve, Georges Ifrah seems more persuasive. He argues that the twelve-part numbering system, like the related sixty-part numbering system, goes back to a long-established and widely used finger-counting method. As he puts it, the “duodecimal finger-counting method used in India, Indochina, Pakistan, Afghanistan, Iran, Turkey, Iraq, Syria and Egypt” involves counting to twelve. One does this by using the thumb of the right hand, beginning with the outermost of the three bones at the tip of the little finger. The sexagesimal finger-counting method, still used in most of the same countries, is complementary to the duodecimal one. It uses the left hand to indicate twelve, twenty-four, thirty-six, forty-eight, and sixty by closing down each of the five fingers, starting with the little finger and finishing with the thumb. Understandably, Ifrah feels that the duodecimal finger-counting method may have been a factor in leading the ancient Egyptians to divide day and night each into twelve unequal or temporal hours. It may also have “led the Sumerians, and the Assyrians and Babylonians after them, to divide the cycle of day and night into twelve equal parts (called danna, each equivalent to two of four hours), to adopt for the ecliptic and the circle a division into twelve beru (30° each), and to give the number 12, as well as its divisors and multiples, a preponderant place in their various measurements.”

posted by XMLicious at 12:59 PM on February 18, 2016 [3 favorites]

You can also count in hexadecimal if you touch each line on the inside face (plus the tip) of each finger with your thumb. This only goes up to 0xFF though.
posted by ArgentCorvid at 12:59 PM on February 18, 2016 [1 favorite]

See also: Chisenbop
posted by anastasiav at 1:03 PM on February 18, 2016 [1 favorite]

I'm just not sure what problem this solves

I do it to annoy people.
posted by Gerald Bostock at 1:05 PM on February 18, 2016 [4 favorites]

Two hands huh?

ASL can get you there on one. And it's pretty intuitive.

Also, I like the way EyeSignUSignASL signs.
posted by Time To Sharpen Our Knives at 1:06 PM on February 18, 2016 [4 favorites]

Yes, the four problem is why I was waiting to teach the kid this.

As for why: The world runs on bits, now. Program, as they say, or be programmed.
posted by one weird trick at 1:07 PM on February 18, 2016 [1 favorite]

Man this is meant for someone with better manual dexterity than I have. I can't easily form many of the combination involving the ring finger without rearranging my fingers with my other hand.
posted by Bulgaroktonos at 1:08 PM on February 18, 2016 [1 favorite]

though for large numbers, it can be uncomfortable to hold those positions for extended periods.

It might be worth it to just treat your pinky and ring finger as the same.
posted by a snickering nuthatch at 1:09 PM on February 18, 2016

I do something like this! I really only use my right hand (31's more than enough... if I need to count to 1023, surely there's some better way). I use the pinky as the least-significant-bit, and usually do it on a surface (so, a finger that touches a table is a 1). I just use it as a quick way to count things, I've never tried to do arithmetic that way.
posted by bfields at 1:15 PM on February 18, 2016 [1 favorite]

I used to be better at this, but I fell out of practice. Once you've done it a few times, it's not nearly as awkward as it first seems.

IIRC, there's an extremely easy method to do basic arithmetic this way, as well.
posted by tobascodagama at 1:47 PM on February 18, 2016

I'm pretty sure this was what I was thinking of.
posted by tobascodagama at 1:47 PM on February 18, 2016

Thanks for posting this. I learned this trick a long time ago and it really helped in visualizing and understanding binary. Helped a ton actually. Would be great for kids as long as you're willing to let them giggle uncontrollably for a while when they reach 4.
posted by honestcoyote at 1:48 PM on February 18, 2016 [2 favorites]

you can get even higher (59,000) with finger ternary.

in ternary hand counting 168 is the devil's number, and 13776 is double devils

hint: 0200220020, yes I spent way longer than I should've figuring that out
posted by numaner at 1:51 PM on February 18, 2016 [2 favorites]

I always do the "Fingers on right hand are worth 1, right thumb is 5, fingers on left hand are 10, left thumb is 50". It works well, and avoids the whole conversion & offensive gestures thing.
posted by LiteS at 1:53 PM on February 18, 2016

Be careful you don't offend anyone when you hit 4, 128 and especially 132.

In ternary, watch out for 18, 4374, and 4392
posted by numaner at 1:54 PM on February 18, 2016

"Fingers on right hand are worth 1, right thumb is 5, fingers on left hand are 10, left thumb is 50"

hand abacus!
posted by numaner at 1:54 PM on February 18, 2016 [4 favorites]

19! Rock on! 11001!
posted by clawsoon at 2:00 PM on February 18, 2016 [2 favorites]

> I'm just not sure what problem this solves
> I do it to annoy people.

Metafilter:
posted by a halcyon day at 2:02 PM on February 18, 2016 [7 favorites]

19! Rock on! 11001!

I think that should be 10011.
posted by Michele in California at 2:03 PM on February 18, 2016 [1 favorite]

[looks at hand]

Dammit. Bit endianness issues.
posted by clawsoon at 2:09 PM on February 18, 2016 [3 favorites]

As for why: The world runs on bits, now. Program, as they say, or be programmed.

Oh yeah? Did a Belgian taxi driver tell you that recently or something, Mr. Friedman?
posted by clockzero at 2:12 PM on February 18, 2016 [5 favorites]

Used to do this in high school when I played pit orchestra for the musicals. It's kind of handy when you have a score with 64-bar rests all over the place.

Now it's just a vestigial fidget , or sometimes a way to temporarily take note of a number because I still haven't learned to memorize numbers quickly.
posted by sibilatorix at 2:18 PM on February 18, 2016 [3 favorites]

I so used to do this as a teenager. I'd built a radio that was tuned by a ten-bit binary number, which was input by ten slide switches, so to set a particular frequency I had to subtract the offset of the radio's frequency at binary 0, divide the result by the frequency step and convert to binary. After a while doing this, I started to think about things in binary to start off with, and could add or subtract with the occasional shuffling of fingers.

But then again, who hasn't?
posted by Devonian at 2:28 PM on February 18, 2016 [2 favorites]

I used to teach this to my middle school students. Good times, and a good way to get the hang of how binary works.
posted by asperity at 2:32 PM on February 18, 2016 [3 favorites]

I still remember my 3rd grade teacher not understanding how I totally got binary and hexadecimal, and had no idea how long division worked.

hint: you can't cheat in Ultima with long division.
posted by Sphinx at 3:02 PM on February 18, 2016 [7 favorites]

On doing basic arithmetic with finger-binary:
The trick with adding two numbers this way is in realizing that the carry from any column will never exceed 1. Then you can add basically the same way that computer arithmetic units do it, as an XOR with carry step.

For each digit (figurative and literal), if either but not both is 1, then the result is 1. If both digits are the same, then the result is 0. If both are 1, remember to carry to the next digit up.

So, 6 + 11 (C means carry):

00110
01011
_____
011C1, so do carry and propagate until we reach a 0....
_____
10001 -- 17

It may sound complicated, but with practice it can be done very very quickly. You can do it with signal lines and logic gates, and I wired up such an adder back in Computer Architecture class for an exercise.

Multiplying and dividing by powers of 2 is even easier. Just "shift" your extended fingers up or down: 1 becomes 2, 2 becomes 4, 4 becomes 8 and so on for multiplying, and the other direction for dividing. Do this once for each power of 2: once for x or /2, twice for 4, three times for 8, etc.

The relative ease of doing arithmetic in binary is one of the reasons computers use it for representation in the first place.
posted by JHarris at 3:27 PM on February 18, 2016 [4 favorites]

The relative ease of doing arithmetic in binary is one of the reasons computers use it for representation in the first place.

i'm not sure i agree, tbh. i think binary simplifies the electronics. anyway, while looking for support for that argument i stumbled across the concept of radix economy which i had been struggling with since first reading this thread (what is better a lot of fingers, or fewer fingers that can bend in more places? - i think radix economy is kind-of-maybe a formalisation of that question)
posted by andrewcooke at 3:52 PM on February 18, 2016

There are 10 types of people in the world.

Those that understand binary and those that don't.
posted by Samuel Farrow at 4:44 PM on February 18, 2016 [2 favorites]

> Oh yeah? Did a Belgian taxi driver tell you that recently or something, Mr. Friedman?

Not that much a Kinky fan myself, but we can slot you in for the latter all the same.
posted by one weird trick at 5:39 PM on February 18, 2016

My math-loving dad has one of these binary clocks. It's fun to keep an eye on.
posted by Pope Guilty at 5:59 PM on February 18, 2016 [2 favorites]

Damn, this makes my ability to go to 99 using Chisanbop look WEAK AS HELL
posted by edheil at 6:09 PM on February 18, 2016 [2 favorites]

Apropos of nothing, I am taking an Intro to Computer Science class, and it has taught me that converting things between decimal, binary, octal and hexadecimal is a really fun way to kill time in boring meetings.
posted by ArbitraryAndCapricious at 6:10 PM on February 18, 2016 [2 favorites]

Apropos of nothing, I am taking an Intro to Computer Science class, and it has taught me that converting things between decimal, binary, octal and hexadecimal is a really fun way to kill time in boring meetings.

Why do CS students always confuse Christmas and Halloween?

Because OCT 31 = DEC 25!
posted by Pope Guilty at 6:29 PM on February 18, 2016 [9 favorites]

"Used to do this in high school when I played pit orchestra for the musicals. It's kind of handy when you have a score with 64-bar rests all over the place."

Hah, in fact, music is mainly what I use it for too.

The fact that bars tend to be grouped in powers of two's might help, I don't know.
posted by bfields at 6:41 PM on February 18, 2016

OK, this is kind of crazy. I started doing finger binary counting the way the video showed, and in just a few minutes my fingers "learned" how to do it and it became totally intuitive. I guess the "flip everything up to & including the first unraised finger" thing really is easy.

It's not as effortless as chisanbop but it's wild how simple that was.
posted by edheil at 6:42 PM on February 18, 2016 [1 favorite]

Finger binary is for babies. It's mad inefficient to have to move all those fingers at once when incrementing from e.g. 63 (0000111111) to 64 (0001000000).

Real nerds are distinguished by their ability to count in binary on their fingers using a Gray code, in which only one digit moves per increment.
posted by liliillliil at 5:51 AM on February 19, 2016 [2 favorites]

Someone should offer a series of high-tech finger tattoos that would help you count to 123 million.
posted by sneebler at 8:01 PM on February 19, 2016 [2 favorites]