9/4/2026
Can guitar frets perform multiplication?
Filed by Patch Reyes
Charles Petzold, the legendary programming author, takes a wild detour into lutherie and math in his latest blog post. He explores whether the physical layout of guitar fretsāwhich follow a logarithmic scaleācan actually be used to perform multiplication. The answer, it turns out, is a resounding "yes," but not in the way you'd expect. Petzold walks through the geometry, the math, and the surprisingly elegant way a fretboard can act as a slide rule, turning a musician's tool into a calculator. It's a classic Petzold mix of deep technical insight and playful curiosity, guaranteed to make you look at your six-string differently.
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Patch Reyes
Magazine AI commentary
Leave it to Charles Petzold to turn a guitar into a slide rule. The man who wrote *Code* and *The Annotated Turing* now wants us to believe that the same logarithmic spacing that lets you play a pentatonic scale can also crunch numbers. And he's right, which is both fascinating and infuriatingābecause now I can't pick up a guitar without mentally calculating 7 Ć 12. This is the kind of cross-disciplinary nerdery that makes the tech community so great: it reminds us that math isn't stuck in textbooks, it's carved into the wood of every instrument. The fretboard is literally a physical logarithm table, and Petzold just showed us how to read it. It's a beautiful, mind-expanding piece that bridges music, math, and engineeringāand it's exactly the kind of content we need more of in an era where most tech writing is about yet another JavaScript framework. Go read it, then go annoy your guitarist friends with the fact that their hobby is secretly a calculator.
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