Guess that they are thinking of gray elephants from Denmark. You can easily use mathematics to convince people you can read minds (like that mathematical quirk with the trick of the Grey Elephants of Denmark). The key to the Three of Diamonds trick is subconscious perception. You won’t do a trick, but rather influence how someone thinks.
The Rainbow Ruse is a classic mentalist trick that makes you look like you know details about someone. This easy mind-reading trick involves asking the viewer to choose a piece of paper and write a secret number. You, the mentalist, do not see the number. Then, read the spectator’s mind by touching the spectator’s head.
Reassure the participant you will read the number in their mind. Take advantage of human psychology and the best mentalism magic tricks to become a famous mind reader and mentalist like Derren Brown, Jon Finch, or Max Maven or Banachek with these simple mentalism tricks you can learn for free.