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by eihli 2223 days ago
I've had a feeling that certain state scratch off lottery games can be beaten thanks to certain actions the states take in the name of transparency. For example, they publish daily reports of the number of prizes remaining.

A simple example is imagine a game with 10 tickets sold for $1 each and a single $9 grand prize.

If 1 ticket is sold each day and if the lottery publishes the number of remaining winning tickets each day, then you can just wait 1 day and if 1 ticket was sold and 9 tickets remain and the prize wasn't claimed, well now there is a 1/9 chance of winning $9 and the expected value is even.

I started scraping several state for daily numbers and calculating the expected value of each game. Every now and then one gets over 100% EV. (Not taking into account annuity discounts and taxes)

https://scratchoff-odds.com

It's also an excuse to try out a lot of different technology and patterns that would be too experimental for most real jobs, so it's a great side project.

I'm currently working on a user section with Clojure, Fulcro (https://fulcro.fulcrologic.com/), and Crux (https://github.com/juxt/crux).

Another fun little side project that was also an excuse to work with Clojure was https://ezmonic.com/. The app was built with ShadowCLJS, Re-Frame, and ReactNative. I've used the Major System mnemonic to remember things like my credit card numbers and I've always wanted to know how optimally short the mnemonics I come up with are. That app uses the CMU phonetic dictionary to search for an optimal phrase.

2 comments

Both projects seem really cool!

Re: Ezmonic, would be cool to have a live version on the website, so I could try out some numbers that are personally relevant and see if I could remember the system, before deciding to download the app.

A web version was my first iteration. It's pretty barebones, but it's available. http://ezmonic.net (Note that it's only served on `http`, so don't put any credit cards in there.)

It's a good idea though to add a web version to the "marketing" page at ezmonic.com. I'll add that to my todo list. Thanks!

Very cool! Wonder what the stats are on how long a winning ticket goes unclaimed. Like maybe the winning ticket has been sold already but not yet claimed.
You're right :) I do have a calculation for "lag" of tickets over a certain amount. Most states require tickets over $600 to be claimed at a lottery headquarters, not a gas station, so there is a noticeable lag in the percentage of remaining tickets over that value. I average out that lag per state, adjust the remaining tickets, and round to the nearest whole number.