Math & words

Double It!

One penny. Thirty days. Doubling gets out of hand fast.

Watch on YouTube
Double It!3:28

A song. A few new discoveries.

Explore exponential growth with a doubling penny, folded paper, a chessboard legend and a musical loop that keeps growing. Slow, slow… whoa!

Day 1 starts at one cent, so Day 30 comes after 29 doublings: $5,368,709.12. The paper-to-the-Moon example is theoretical and assumes paper about 0.1 mm thick. Real populations and savings do not double forever at a fixed rate; this is a math thought experiment.

Made for curious kids around ages 6–12 and the grown-ups watching with them. Music and animation created with AI tools under Mike Sego’s direction. YouTube’s video description includes the release notes and credits.

Read the sing-along lyrics
Smarty Party! A million dollars, right now? Or one penny that doubles every day? For thirty days. ...I'll take the penny. Day one, one penny, shiny and small, Day two, two pennies—that's nothing at all! Day ten, five dollars—still kind of a joke, The million-dollar kid says, "Ha! You're broke!" Day twenty, five thousand—hey, look at that! Day twenty-eight, a million! Tip of the hat! All from one penny that doubled, slow-slow! Double it! Double it! Two, four, eight—keep going! Slow, slow, slow, slow... Whoa! Now look at it growing! Double it! Double it! Double it again! Take a sheet of paper, fold it in half, Every fold doubles it—go on, do the math! Most people get stuck at seven or so, But a high-school student folded twelve! Let's go! If you could fold it forty-two times, oh my, That paper would reach the Moon in the sky! Double it! Double it! Two, four, eight—keep going! Slow, slow, slow, slow... Whoa! Now look at it growing! Double it! Double it! Double it again! Two, four, eight, sixteen, thirty-two! Times two! Times two! Oh-oh! An old, old legend: a king and a board, "Inventor of chess, pick any reward!" "One grain of rice on the very first square, Then double it, square after square." But by square sixty-four—oh no, oh no— He'd owe more rice than the world could grow In hundreds of years! Whoa! Some two dozen rabbits let loose Down Under Became hundreds of millions—a hoppy blunder! Save up some money, and it earns a bit more, Then that more earns more—that's compounding, for sure! Slow, slow, slow... then whoa, whoa, whoa! Stack every loop, and here we go! Double it! Double it! Two, four, eight—keep going! Slow, slow, slow, slow... Whoa! Now look at it growing! Double it! Double it! Double it! Double it! Double it again! Two, four, eight, sixteen, thirty-two! Times two! Times two! Oh-oh! Day thirty. Let's count my penny. Five million... three hundred sixty-eight thousand... seven hundred nine dollars... and twelve cents. ...Can we do day thirty-one? Smarty Party Songs! Like, subscribe, PARTY!

Lyrics from the published video’s caption file.

Keep the discoveries coming.

For the grown-ups

Keep the discoveries
coming.

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