I’ve been wondering about how one could count and show numbers with only one hand and without relying on repeating or cutting in parts. After being unable of getting rid of this brainworm, I decided to write about this system.
1, 2, and…
The basis of this digital system is to use different finger positions in a way that can immediately express a specific number, with a variance going up to 100 by itself, and some exceptions. The different finger positions used are pointed, half, and removed(half being a finger folded like a hook, with only the base standing out). The hand itself will be either up, or down. Horizontal position and facing being excluded as to avoid positional confusion for both observers.
First Digits
We begin with the hand in up position, all fingers being removed, showing a raised fist that represents 0. Then the thumb pointed represents 1. Removing the thumb, showing the index pointed is 2. Middle finger pointed is 3. Ring finger pointed is 4. And finally pinky finger is 5.
So far it should be quite simple as it follows a fairly natural order to count numbers. However now things become slightly more, as we’ll have to represent 6 to 10 with the same hand. To do so, we’ll have to turn the hand in down position. Then, we repeat the previous steps, but starting from 6. Meaning that thumb pointed down is 6. Index finger pointed down is 7. Middle finger pointed down is 8. Ring finger pointed down is 9. Pinky pointed down is 10.
This is quite straightforward, and will become the foundation of the whole system as we will see when we enter more advanced numbers. It is also important to note that unless specified, the implied state for the hand is up, a finger is pointed, and every non mentioned finger is removed when displaying a number(however if a finger is mentioned as removed, then other fingers default to pointed).
Tens and Beyond
Now that we have our first 10 numbers, how can we display further? There are a number of quirks as well to fit this many numbers on only 5 fingers.
The first one is for mirror numbers, 11, 22, 33, etc… to 99. As those numbers require the same finger to be used twice, it’s expectedly complicated to represent that properly. So a shortcut is used, and a single half finger will represent its corresponding mirror number. Meaning that thumb half is 11, index half is 22, middle half is 33, ring half is 44, pinky half is 55, thumb half down is 66, index half down is 77, middle half down is 88, and then, because you only have 9 mirror numbers total, and that the ring finger is the hardest to make stand out on its own let alone as half, we skip directly to pinky half down is 99.
Following a different system, the round tens after 10 have an exclusive rule too. They cumulate pointed fingers so that no other setup can be mistaken for it. Thumb and index is 20, thumb index middle is 30, thumb index middle ring is 40, all fives fingers is 50. Thumb index down is 60, thumb index middle down is 70, thumb index middle ring down is 80, all five fingers down is 90. Finally 100 is all five fingers half hand up(it looks like a hand claw), while a bonus exception for five fingers half hand down represents 1000.
The Filling
Now that all mirror numbers, first ten and the tens beyond are all ‘mapped’, what’s left are the 8x9 remaining numbers. Only a few set of rules will be able to display all of those. To answer this, the main rule for bigger numbers is that we will be using two fingers to display both the 10s and the units of the number. The tens will be pointed while the units will be half.
As an example past 10, 11 is skipped as it’s a mirror number, then 12 is thumb pointed index half, 13 is thumb pointed middle half, 14 is thumb pointed ring half, 15 is thumb pointed pinky half. The pattern is the same for any tens, however the mirror number will vary in position.
For the second half of the tens however, things become slightly more complicated as we have 4 numbers to display requiring the same hand. To solve this, we will have to invert the displaying of fingers. The tens finger will be removed, keeping the units finger as half, while the ‘unused’ fingers are all pointed.
So for 16, you will have thumb removed index half (and implicitly all three remaining fingers pointed, which is the case whenever a finger is mentioned while removed), 17 is thumb removed middle half, 18 is thumb removed ring half, 19 is thumb removed pinky half.
With this, we circle back and start anew for 21 with index pointed thumb half (the tens finger is mentioned first to keep things clear). Skipping 22 this time, the rest follows the same rules as before. 50 and beyond being the same pattern with the hand in down position instead, an extra rule is necessary to balance the fact the mirror number is in the latter half. We will signify the first 4 numbers with the pattern. Then proceed with the 4 remaining ones in inverted pattern, but starting from 5.
So 81 is middle pointed thumb half down, 82 is middle pointed index half down, 83 is middle pointed ring half down, and 84 is middle pointed pinky half down. For the second part, 85 is middle removed thumb half down, 86 is middle removed index half down, 87 is middle removed ring half down, skipping 88 as the mirror number(middle half down), and 89 is middle removed pinky half down.
Results
While I acknowledge this system is a bit convoluted, it allows you to communicate any number from 0 to 100 following a set of rules, using only one hand and visual information to transmit. If speaking is difficult in that moment, and with the need to quickly transmit numbers with one hand, it might just help you!