00:01
We're a bunch of things about prime numbers.
00:05
And we can, basically, this prime pie, which i will call it prime pi, basically it says that how many prime numbers are there below a certain number here? so a certain integer.
00:24
And so they ask us, calculate the number is pi to the pie of 25 and pi of 100.
00:32
Well, we can, pi of 29, again, they tell us to use the sieve of aristotasins.
00:43
Yeah, i can't remember how, i don't know how to pronounce that exactly.
00:50
But it basically says just divide by two, get rid of all the even numbers, then divide by three, get rid of anything that's a multiple of three.
00:59
And then we divide by the next, that's five, we get rid of all the multiples of five, then get rid of all the multiples.
01:04
Multiples of seven then get rid of all the multiples of 11 i keep doing that until we get up to at least you know halfway through and that would be that there'd be possibly no more if we get up to 50 you can't there will be no more prime numbers after that we divide it as once you nothing divides by 50 so for 9 we get 1 for 25 we get 2 3 5 7 11 13 17 and 19 and 23 so you get 9 there's 9 prime numbers less than, is it less than or equal to? primes that are less than or equal to, yeah, 25.
01:43
So 100, we need to do a little more work, and we can find that, in fact, we get then 29, 31, 37, 41, 43, 47, and so on.
01:54
And counting all these up, we get 25.
01:56
So there's 25 primes that are less than are equal to 100.
02:00
And there's 25 primes that are less than 100, too, because the highest, the largest one is 97.
02:07
Now, they say, okay, they tell us that gauss, when he was a teenager, said that the, postulated, at least, that the limit as n goes to infinity of pi to the n divided by n over the natural log of n is one.
02:27
And then 100 years later, that was actually proven.
02:32
I'm not sure how you actually prove that.
02:34
That's, that's what would be quite an interesting.
02:38
Interesting proof to try to work through.
02:40
But anyway, we'll just actually even just see how it was done.
02:44
So they say, well, let's do this for a few values.
02:47
So we get for 100.
02:50
We have, so this is 25.
02:54
And then we have, you know, 100 times the natural log of minus 100.
03:01
So n over a natural log of, n over natural log of n.
03:08
So we just brought that up under the numeral.
03:10
And that gives us 1 .15.
03:15
Okay, so it's close to 1...