Name: Glitch Primes and Cyclops Numbers - Numberphile
Uploaded: 2020-03-30T05:06:26.000Z
Duration: 13 min 32 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Past simple

I posted something on Twitter a while ago

with a lot of digits that are all the same

All nines. You can see it. In actual fact,

the way that you'd describe this is as a repdigit.

So, in the maths canon you'd say repdigit, meaning "repeated digit".

There's two things really special about this number

down here, there's one digit that's changed

But you know what I like to call it, Brady?

Believe it or not, this is a prime number.

As a mathematician, that's what you wanna do, you want to check it.

The only problem is: how do you check a number like this?

I- I really don't suggest you stick this into the Google entry line.

To actually work out if it was a prime or not,

I needed to actually transform it into something that I could carry around

From the ones column, and the tens column, and the hundreds column

If you get up, you actually get to the 254th column

How can we actually transport this in a way that doesn't involve me writing out all these nines?

What's really cool about it is the fact that they are nines.

And, if you add 1 to 999, you get a thousand.

well, that can really make things a lot easier for us to handle.

-- You gotta love the dot-dot-dots, because you can put anything in dot-dot-dots --

is equal to... -let's just jump to the chase, hey, Brady?-

... is equal to nine-nine-nine, dot-dot-dot,

BRADY: I know that's a small change, but that actually changes the value of the number quite a lot, doesn't it?

SIMON: What do you mean, "changes the value"?

BRADY: The quantity, like, if you were going to buy that many eggs...

SIMON: [laughs] You wanna put this into eggs?

Changing that from a 9 to an 8 will dramatically change the number of eggs you just bought.

SIMON: Well, you know what? You're exactly right,

So, if we actually think there's a 9 right there,

So what would that mean? That means that we're actually taking away 1,

for every 9 there's basically a 0, because that's continuing what's going on here.

Subtitles ListPlay Video

Glitch Primes and Cyclops Numbers - Numberphile

sort

recommend

pattern

basically