The great thing about the Mental Calculator is that you can use it as a normal calculator. You control the number that you want to force (up to 8 digits), and you can change it every time to suit your needs.

The Recollection Technique - This technique and the Eight Observations that led to its development will change your magic forever! It forms the foundation of all Tony's work, and can be used in the construction of everything from a single effect to an entire performance! With this calculator, you can create many mind-reading effects. You write a prediction. Several spectators are asked to freely write down numbers and to make different kinds of calculations with these figures (multiply, add, deduct, etc.) using the calculator. The final result that they obtain with the calculator will match your prediction! The great thing about the Mental Calculator is that you can use it as a normal calculator. You control the number that you want to force (up to 8 digits), and you can change it every time to suit your needs. Spectators can check the calculator even after you have entered your secret number.