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Monday, February 24, 2020

Let me count the ways


58 and other Confusing Numbers - Numberphile

I have seen a couple other Tom Scott videos and he's not bad. A little too enthusiastic, but then he's young and the young are supposed to be enthusiastic. That's how anything gets done. He's right, number systems are weird, and he doesn't even touch on how European millions are American billions, and trillions are billions. I don't even know which is which. I stick with what I know, and on this side of the pond a million is a thousand times a thousand, and a billion is a thousand times a million.

Much popular science fiction, when it involves aliens, often makes them out to be similar enough to humans that they will have conflicts. I suspect that real aliens will be hard to detect. They will be so weird that we won't even recognize them as life forms, much less intelligent life forms.

Not all videos I see get posted here. I have to be able to watch them. There are a bunch out there that look like they would be interesting, but start playing them and in 30 seconds I've had enough. Mostly it's the voice. Sometimes it's the format (I'm going to tell you all about just as soon as I get done telling all this other stuff). Some people just take forever to get to the point. But that's me.

I'm working on a palindrome program, but I've reached a point where I need to think clearly, and I didn't get enough sleep last night so I can't wrap my mind around the problem, so I think I'll tell you about it.

We are trying to find a number that has the characteristics of a palindrome, where  you get the same number forward or backward, like 1234321, that is smaller or equal to another number. The first thing is to take the first half of the digits of the given number, reverse them and make them the second half of the number. Say you were given 1234567, you take the first half, 1234, reverse it, 4321, and then replace the last four digits of the given number, and surprise surprise, we get the same number as in our example earlier: 1234321. Okay, the four is replaced with a four, which we really didn't need to do. In any case our new number is less than our given number, so we're golden.

But now, say your given number is 1004000. Now it gets a little sticky, and I'm getting hungry, so I'm just gonna leave you with this little puzzle. This is where I need a clear head.

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