With these Mental Logs, you become a Human Computer who can add faster than any calculator.
The rods are rolled like dice to create four 4-digit numbers. You ask your spectator to add up the four numbers, and as they begin to punch numbers into the calculator, you announce the total! And you're correct!
It can be repeated as many times as you like, as there are over 6000 possible totals! You can even predict what the total of the four numbers on the reverse side will be before you've seen them!
Beautifully made, with engraved numbers on anodised metal rods.