Forcing Calculator

Key benefits
Force any number with the equals button

Quick set using the memory function

Looks and behaves like a standard calculator

Participant does the tapping, you stay hands off

No sleight of hand

Instant reset

The Effect
You introduce a calculator and hand it straight to your participant.

You talk about how people trust numbers because maths feels objective. Then you have them type in a short string of numbers. Those numbers can come from the room, their choices, or whatever feels natural in the moment.

They press equals.

The display confirms the outcome you wanted.

Now ask yourself, what hits harder: a force that happens in your hands, or a force that happens in theirs?

Why this is a worker
This is not a “trick calculator”. It looks right. It feels right. It behaves like the one that lives in a kitchen drawer.

It also solves a real problem. You can cleanly lock in totals for predictions, add-on revelations, book tests, serial number reveals, drawing duplications, lottery-style routines, and any routine where a number needs to feel fair because they did the input.

Close up or parlour, it plays strong because it is direct, simple, and hands off.

Options
Choose your display style:

Visible M
The standard memory indicator shows when a force is set.

Taped M
The “M” is hidden for a cleaner display (suggested by Richard Osterlind).

Specs and practicalities
Power: 1 × AA battery

Setup: quick set via memory

Reset: instant

Venues: close up and parlour

Skill: no sleight of hand, no timing pressure, just simple audience management

Requirements
One AA battery (for orders outside the UK the battery is not included).

History and credits
The core idea in this style of forcing calculator dates to 1975, with early uses by John Sherwood, Bayard Grimshaw, and Vic Perry.

Thank you to Mark Strivings for help with crediting.

Get it and start forcing numbers

If you want a clean utility that feels like real life and hits like a prediction, this earns its place in your case.