The first math skill you learned as a child was probably counting. The natural numbers: 1, 2, 3, and so on. The second was arithmetic. 2+2, 8 times 5, and so on. These both probably come naturally to you now, but it’s unlikely that your kindergarten teacher ever explained set theory and the successor function while teaching you how to count. That’s what I hope to do here: show you the rigorous foundations of the mathematics you use every day without even thinking.

In ye olden times, the proof of 2+2=4 probably went something like this:

“I have two apples…

Josh Gammage

Sometimes combines words and punctuation in an interesting pattern

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