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neallindsay

I love a good math article where "digital" means "base 10".

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It's a property referencing the digits - thus "digital". The results hold for all bases, not just base 10.

Digit = finger. Most people have 10. It was a pun.

I have a 2 handed phone number

Toes are also digits.

Whether the thumb and big toes are fingers is something that depends on definitions, but in the strictest sense they are excluded from fingers and toes, and thus humans generally have 20 digits, eight fingers, and eight toes by this definition.

I thought the joke was that digital = binary = 10 :)

Every base is base 10.

I laughed at that a lot more than I should have. After a long day, thank you for that.

The origin may be this comic: https://web.archive.org/web/20090125051251/http://cowbirdsin...

The origin was probably thousands of years ago; it's a basic property of positional number systems.

nice detail on the alien having 4 digits.

But every base is not described in the base most commonly written for human reading as "base 10"

Saving other non-math people like me a web search explaining this: https://blogs.scientificamerican.com/roots-of-unity/the-funn...

I actually ran into this once not as a joke. I was using some software which had an option that would change the default base it used for all numbers. After typing <command> 16 and fiddling about in hexadecimal I tried switching back to decimal using <command> 10, yet I was still in hex mode. It took me a few more seconds than it should for me to realise what had happened.

It must be the command-line calculator bc

That's possible, it was a long time ago and I can't remember for sure

Except for base 1.

Nice corner case. It's pretty much useless, it would contain just a single value. Is it even valid base?

https://en.wikipedia.org/wiki/Tally_marks

It can actually represent all integers just fine. It works like any other base, except whereas for example in base 10, positions are multiplied by 10^0 = 1, 10^1 = 10, 10^2 = 100 and so on, in base 1 they are multiplied by 1^0 = 1, 1^1 = 1, 1^2 = 1, and so on. The result is that each digit adds 1 to the number, like tally marks. So we have, for example

111 = 3

11 = 2

1 = 1

= 0

-1 = -1

-11 = -2

-111 = -3

That is wierd. Base k includes numbers 0,...,k-1. For example 101 is a valid number in base 2 which is 2^2 + 2^1.

Using that logic, base 1 would only contain 0, hence it should not be able to expresss more values that 0.

Is your example actually a valid base 1?

All your base are belong to us.

Except in Common Lisp, where every base is base 10, but only one base is base 10. .

Every base is base "one zero"; not every base is base "ten".

Yes, the word for base 10 is “decimal” [1] and digits do not have to be decimal digits. There are also binary digits “bits” [2], ternary digits “trits” [3], and so on.

[1]: https://en.wikipedia.org/wiki/Decimal

[2]: https://en.wikipedia.org/wiki/Bit

[3]: https://en.wikipedia.org/wiki/Ternary_numeral_system

How does it hold in base 2? Wouldn’t changing the least significant digit always make any prime an even number?

digits we have, most 10.

Primes are the same irrespective of base...

Is this true for digitally delicate primes as well?

Different primes will be delicate in different bases (you can trivially demonstrate this by considering a prime n in base n-1) but they exist in all bases.

A prime might be 'delicate' in base 10 but not be delicate in base 8.

Another prime might NOT be delicate in base 10 but be delicate in base 8.

Right that’s explained in the article. I assumed OP only read the headline and assumed “digital” meant binary rather than an actual digit.

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