Magic & Math with Cards

Lecture 04 · Performance

Baby Hummer

Four cards refuse to stay mixed

Video in production

This lecture is still face down. Its script is written; filming and animation are under way.

Meanwhile, play the trick

What you will learn

Perform Baby Hummer and explain its selected-card revelation using the opposite-position mate relation.

The trick in this lecture Baby Hummer Four cards, mixed by your own hands. Your card ends up as the one facing the other way. Play the trick

Before this lecture

Ideas you will use

  • Cut and packet turnover

In this lecture

An outline of the lecture, scene by scene, with the statements that appear on screen. It follows the draft script, so details may change in production.

  1. Establish selection and runnable preparation

    At the table
    • Remember bottom card
    • Top to bottom
    • Flip new top in place
    • Cut, then turn top TWO TOGETHER

  2. Allow real spectator choices and perform exact finish

    At the table
    • Finish: flip + move
    • Then move without flip
    • Then flip in place
    • The selected card is the exception

  3. Repeat transparently and isolate the mathematical question

    At the table
    • Reset all four face down
    • Opposite positions: 1↔3, 2↔4

  4. Verify exact setup and define mates

    • Setup: 2↑, 3↓, 4↓, A↓
    • Selection 4 and oddball 2 are mates
    • Mates: positions 1&3 or 2&4

  5. Prove mate preservation under top-pair turnover

    • Case 1: oddball inside top pair
    • Case 2: oddball outside top pair
    • Selected card remains mate of current oddball

  6. Explain the finishing procedure as a parity-class toggle

    • Finish toggles original positions 1 and 3
    • One mate pair flips
    • Either case: selection becomes oddball

  7. Trace one exact round and diagnose a near-miss

    • Worked cut sizes: 3, 1, 2; final cut 3
    • Final: 4↓, 3↑, A↑, 2↑
    • Audit the move, not the luck

  8. Specify playable performance and explanatory challenge

    • Choose cuts; preserve the protocol
    • Predict the next oddball
    • Finish toggles a mate pair

Companion interactive

Reveal the secretly remembered bottom card and explain the mate invariant.

The trick page is this lecture’s companion: be the spectator, lift the curtain to step through why it works, try the challenge, then learn the handling.

Open Baby Hummer

Sources

How these sources were used
  • Persi Diaconis and Ron Graham, Magical Mathematics: Charles Hudson Baby Hummer; exact setup and finishing instructions retained; original narration.