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If you’ve watched a mentalist perform and found yourself wondering “how did they know the volunteer would pick that number?” — the answer is almost always a force. A mentalism force is one of the most powerful tools in any performer’s toolkit, and the good news is that most forces are surprisingly easy to learn.
In this guide, you’ll discover exactly what a mentalism force is, why they work on nearly everyone, and six specific techniques you can start using right away — even if you’ve never performed mentalism before.
What Is a Mentalism Force?
A mentalism force is any technique that gives your audience the illusion of a free choice while you secretly control the outcome. From the spectator’s perspective, they made a completely random, unprompted decision. From your perspective, you knew exactly what they would “choose” before they made it.
Forces are the hidden engine behind most mentalism prediction effects. When a performer opens an envelope to reveal a number that perfectly matches what a volunteer “freely” thought of, a force was almost certainly at work. Understanding this one concept transforms the way you watch — and perform — mentalism.
Forces fall into three broad categories:
- Mathematical forces — sequences where the arithmetic always produces the same result, regardless of what number the spectator starts with
- Psychological forces — subtle verbal and visual cues that guide someone toward a predetermined choice without them realizing it
- Procedural forces — structured elimination games where you maintain invisible control over which item survives to the end
Once you understand how each type works, you’ll start recognizing forces in everything from classic mentalism prediction tricks to polished stage performances.
Technique 1: The Gray Elephant in Denmark (Mathematical Force)
This is one of the most famous mathematical forces in mentalism, and it’s an ideal first technique because it requires zero props and works on almost everyone the first time.
Here’s how to perform it:
- Ask your spectator to think of any number between 1 and 9.
- Tell them to multiply that number by 9.
- If the result is a two-digit number, ask them to add both digits together. (It will always be a two-digit number.)
- Tell them to subtract 5 from their result.
- Ask them to match their number to a letter of the alphabet: 1 = A, 2 = B, 3 = C, and so on.
- Ask them to think of a country that starts with that letter.
- Ask them to think of an animal that starts with the second letter of that country.
- Finally, ask them to think of the color of that animal.
Your prediction: “You’re thinking of a gray elephant in Denmark.”
Why it always works: No matter which number between 1 and 9 they pick, multiplying by 9 and adding the digits always produces 9. Subtracting 5 gives 4 — the letter D. Most people jump immediately to Denmark (over Djibouti or Dominican Republic), then elephant for E, then gray. It’s not guaranteed, but the hit rate is high enough to perform confidently. If they go off-script, a relaxed “You had to be different, didn’t you?” earns a laugh and moves things along.
Technique 2: The 1089 Force (Mathematical Force)
The 1089 trick produces the same four-digit number every time, regardless of where your spectator starts. It’s a natural fit for any prediction effect where you show your answer before they begin.
- Ask your spectator to write down any 3-digit number where all three digits are different (for example, 452).
- Tell them to reverse the digits (254).
- Subtract the smaller number from the larger: 452 − 254 = 198.
- Reverse that result: 891.
- Add the two numbers together: 198 + 891 = 1089.
The answer is always 1089, with one edge case: if their subtraction gives a 2-digit result, ask them to place a zero in front (e.g., 099). That reverses to 990, and 099 + 990 still equals 1089.
Present this by writing “1089” on a slip of paper beforehand, folding it, and handing it to the spectator before you even begin. When they arrive at 1089 and unfold the paper themselves, the reveal lands hard.
Technique 3: The Psychological Force (Guided Free Choice)
Psychological forces rely on a simple truth about the human brain: when given an “open” choice, most people default to the most culturally familiar or visually prominent option. You can predict — and use — that tendency.
A few well-documented examples:
- Ask someone to “think of a simple geometric shape” — the majority choose a triangle or circle.
- Ask them to “name a color” — red or blue dominate.
- Ask for “a number between 1 and 10” — 7 is by far the most common response.
You can sharpen these odds with verbal pacing. When you list options, say the one you want to force last, with a slight pause and a deliberate look. People unconsciously weight the final item in a list more heavily than the ones before it. Combine this with a confident, unhurried delivery and you have a simple, convincing force with no math required.
This technique is the foundation of the triangle in a circle trick — a complete beginner routine built on this exact principle.
Technique 4: The PATEO Force (Procedural Force)
PATEO stands for Pick Any Two, Eliminate One. It’s a procedural force that looks like a fair elimination game while keeping you completely in control of the outcome.
Setup: place several objects on a table, one of which you’ve predicted in a sealed envelope. Ask your spectator to point to any two objects. Your secret rule is simple:
- If they point to your predicted object, you eliminate the other one (“We’ll get rid of that one”).
- If they don’t point to your predicted object, eliminate both (“Great, those two are out”).
Repeat until only your predicted object remains. From the outside, the spectator appears to have driven every decision. In reality, you controlled each one.
The key is pacing. Don’t rush to eliminate objects — pause, look thoughtful, act as though you’re responding to their energy. The more natural the elimination feels, the stronger the effect reads to an audience.
Technique 5: The Constrained Choice Force (Guided Probability)
This technique narrows the field of “free” choices down to one or two most likely answers by adding specific constraints to the request.
Try this: ask someone to “think of a number between 1 and 50. Make it a two-digit number where both digits are odd and different from each other.” When you analyze those constraints — odd digits, two-digit, no repeats — the options slim down dramatically. Most people land on 37. Some choose 13, 15, or 19, but 37 is the heavy favorite.
Prepare a folded prediction in your pocket before you perform. If they say 37, reveal it confidently. If they don’t, stay calm — a relaxed pivot (“Interesting — 13, bold choice. Tell me about yourself”) keeps momentum going far better than visible surprise.
Building a stock of these “outs” is one of the most important skills you’ll develop. If you’re just starting out, the guide to getting started with mentalism covers exactly how to think about backup plans and performance recovery.
Technique 6: The Multiple-Out Force (Guaranteed Prediction)
The multiple-out force doesn’t try to control what your spectator chooses. Instead, it ensures you have a winning response for every outcome they might land on.
A classic setup: before you perform, write three different predictions on three separate slips of paper — each corresponding to one of the most likely responses your spectator might give. Fold each slip and hand them to three different audience members to hold.
When your spectator makes their choice, ask that volunteer to open their slip. The other two slips are pocketed or never examined. To the full audience, it looks like you predicted one specific, correct outcome.
This technique requires careful preparation and confident handling. The slips that don’t get opened must never be examined. Keep things moving, build atmosphere after the reveal, and most audiences will never think twice about the others.
How to Present Forces Convincingly
Knowing how a force works is half the job. Presentation is what determines whether your audience is impressed or skeptical.
A few principles that matter most:
- Don’t rush. Real mind reading would require concentration. Take a breath, look like you’re receiving information, give the moment weight.
- Act like everything is new. Even though you know exactly how things will end, your face and body shouldn’t. React in the moment, not ahead of it.
- Reveal, don’t confirm. Instead of asking “Is it an elephant?” say “I’m seeing an image of an elephant — gray, large, somewhere cold.” Let them confirm you. That framing is far more powerful.
- Handle misses gracefully. The gap between an amateur and a professional mentalist isn’t how often they miss — it’s how they respond when they do. A calm, confident pivot always reads better than visible panic.
Frequently Asked Questions About Mentalism Forces
What is the difference between a mentalism force and a mentalism trick?
A force is a technique used inside a trick. The trick is the performance — the prediction, the reveal, the story you tell. The force is the hidden mechanism that makes the trick work. Most mentalism effects use at least one force, and some use several layered together.
Do mentalism forces always work?
Mathematical forces work 100% of the time as long as the steps are followed correctly — the math guarantees the result. Psychological forces typically work 70–90% of the time depending on the technique and the audience. Procedural forces like PATEO are foolproof as long as you apply the rule consistently.
Can a spectator accidentally ruin a force?
With mathematical forces, no — the math is the safety net. With psychological forces, spectators occasionally land on an unexpected choice. That’s why it’s worth having a natural, prepared “out” before you perform, so any response can be handled smoothly.
How do I practice mentalism forces?
Start by running through each technique alone until you know the mechanics without thinking. Then try them on friends or family in relaxed, low-stakes settings. Focus on making your instructions feel natural and conversational rather than scripted. The goal is for the sequence to feel like a fun exercise, not a test.
Are mentalism forces ethical to use?
Yes, in the context of entertainment. Your audience knows they’re watching a performance, and forces are a standard, well-established part of mentalism and magic used by hobbyists and professionals alike. The deception is part of the art form — the same way a novelist invents a story or an actor plays a character.
Which mentalism force should a complete beginner learn first?
Start with the Gray Elephant in Denmark. It needs no props, no sleight of hand, and works on almost anyone. Once you’re confident with that, add the 1089 force. From there, the PATEO force is a natural next step once you have a few objects and a routine ready to build around it.
Forces are the foundation of mentalism performance. Master these six techniques and you’ll have a toolkit that supports dozens of different routines. Pair them with strong presentation and a bit of practice, and you’ll be performing effects that genuinely fool people — even those who consider themselves skeptics.
Ready to build your first full act? Explore our guides to mentalism prediction tricks and getting started with mentalism to put these techniques to work in a complete routine.