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  • - The legend around this chalk is that it's impossible to write a false theorem.

  • - I assume the special ingredient was angel tears.

  • - Mathematicians from all of the top schools very frequently use it.

  • - It's a cult favorite.

  • - As soon as I use it I was a convert.

  • - The chalk is one of the best kept secrets in the math world.

  • - It's the Rolls Royce of chalk.

  • - Hagoromo is a brand of Japanese chalk.

  • The way it flows on a board is a bit hard to describe in words.

  • - It's really hard to get.

  • You can only get it from Japan, you need a Japanese person to bring it back for you.

  • - I discovered it when I went to visit the University of Tokyo and one of the professors there said to me, you know, we have better chalk than you do in the States and I said, oh go on, chalk is chalk.

  • And so I tried it out, and I was surprised to find that he was right.

  • - I tried it, and I thought it was phenomenal.

  • It's the densest, it erases the cleanest,

  • it leaves the nicest line.

  • - If you use bad chalk often you have to press really hard for anyone to see what you're writing so using Hagoromo on a good board, it doesn't really feel like you're working hard to write.

  • - When I'm teaching I get a feeling of energy, confidence, and the chalk absolutely helps.

  • - Slowly the math world has become aware of this, and it became a bit of a fad in some circles.

  • - It was like maybe four years ago the word came out that the company was going out of business.

  • I sort of jokingly referred to it as a chalk apocalypse.

  • So I immediately started hoarding up as much as I could.

  • - I ordered three boxes of Hagoromo and kept it in my office and used it very sparingly.

  • - I should've bought more but I have friends that bought boxes and boxes and boxes of the stuff.

  • They might very well be set for the rest of their career.

  • - We've got like 1,500 sticks.

  • That's a lot of days, four sticks a day.

  • I think I'm gonna make it.

  • - I have probably a 10-year supply still at home.

  • - I calculated how many boxes would I need to last for 10 or 15 years.

  • I didn't wanna become a chalk dealer, but I did like the idea that I could be the first stick is free chalk dealer on the block in my department.

  • - I was probably selling it regularly to maybe eight to 10 colleagues.

  • I would reach into my cupboard in my office and pull out another box and we'd do the deal in my office.

  • Yeah, we all had a chalk fix.

  • And we still do.

  • - The original Hagoromo chalk is slowly disappearing.

  • A few years ago, a Korean company bought their formulas and did the best job of faithfully reproducing it in Korea.

  • - It was mixed emotions.

  • I was happy to know that it would still be made.

  • But I was a little disappointed that I was less clever than I thought I was.

  • - In many ways mathematics is like craftsmanship, in some ways it's like artistry; in some ways it's like science.

  • But there's a real high craft side to getting a beautiful lecture on a blackboard.

  • Mathematicians admire this in each other and like to use the best tools for it.

  • - There's incredible value to this but the value is in using it up, not hoarding it.

- The legend around this chalk is that it's impossible to write a false theorem.

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