Think of a number between 1 and 15, and I'll read your mind!
The Binary Card Trick uses the power of binary number representation to "read your mind".
The Secret:
Example: If you pick cards with values 1, 2, and 8, your number is 1 + 2 + 8 = 11
Binary Representation: 11 in binary is 1011, which means it has 1s in the 1, 2, and 8 positions!