THE LESSON ROOM
Five questions, one quiet thought
Turn binary number cards into an intimate prediction-style reveal, with clear instructions and a presentation that earns the five questions.
WHAT YOUR AUDIENCE SEES
The effect
Someone keeps a number from 1 to 31 in mind. After identifying which groups contain it, you reveal that number without having them say it.
What you need
- Five paper cards
- A pen with clear, large lettering
- Paper for private practice calculations
Your practice goal
Recover every number from 1 to 31, then guide a spectator through all five groups without rushing or losing the total.
I’m here to learn. Show me the method.
First, experience it
Try Five Lanterns in the theater. The mathematics is elementary; this intermediate lesson focuses on handling five decisions, reading an audience, and delivering a single clear reveal. It is a number discovery, not a prediction written in advance.
Prepare the five cards
Write these groups on separate cards, in four rows of four. Keep the first number at the upper left of each card. All numbers must be equally easy to read.
| Card | Numbers |
|---|---|
| 1 | 1, 3, 5, 7 / 9, 11, 13, 15 / 17, 19, 21, 23 / 25, 27, 29, 31 |
| 2 | 2, 3, 6, 7 / 10, 11, 14, 15 / 18, 19, 22, 23 / 26, 27, 30, 31 |
| 4 | 4, 5, 6, 7 / 12, 13, 14, 15 / 20, 21, 22, 23 / 28, 29, 30, 31 |
| 8 | 8, 9, 10, 11 / 12, 13, 14, 15 / 24, 25, 26, 27 / 28, 29, 30, 31 |
| 16 | 16, 17, 18, 19 / 20, 21, 22, 23 / 24, 25, 26, 27 / 28, 29, 30, 31 |
Method
Ask for a whole number from 1 to 31, kept unchanged throughout. Start a mental total at zero. Show each card and ask only whether their number is present. For every yes, add that card’s upper-left number. For no, add nothing. After all five cards, the total is their number. For 22, yes occurs on 2, 4, and 16: the total is 22.
You may reorder the cards, provided you add the actual card’s value and show each card exactly once. Use a separate completed pile to prevent repeating a card. Do not use the current position in your hand as its value.
Why it works
Every whole number from 0 to 31 has a unique sum using 1, 2, 4, 8, and 16 at most once. A card contains exactly the numbers that use its value. Five no answers represents zero, which is outside your stated range. It calls for a gentle restart, not a dramatic claim of success.
Give the questions room
“Each lantern lights a different part of the path. Tell me when you see your number.” Show one group at a time, at a distance the person can read. Wait for a definite answer. For a larger audience, use large printed boards and one volunteer who can see them comfortably; tiny cards are not stage props.
Recovery and checkpoint
If an answer changes, subtract the old yes value or add the new one before continuing. If you lose the total, start openly from the beginning. Do not blame the spectator’s concentration. Check every number from 1 to 31 in rehearsal, then perform three trials with a partner. Pass when they can follow without coaching and you do not speak over their reading time.
Original lantern presentation and performance exercise for the traditional binary-number-card principle. Mathematics and card grids are documented by STEMAZing.
Share the effect, respect the creator, and let people choose whether to learn. Our code →