The performer shows the spectators four small rods with four different numbers on each of their sides. The spectator is invited to toss the rods on the table, assemble them, and then sum up on a Calculator (or on their telephone) the 16 numbers on the top sides of the rods. While the spectator is starting to just digit the first number, the performer immediately calls out the total!
This can be repeated as many times as desired, and always with a different result. The effect for the spectators is that you are a human computer able to add many different numbers in the blink of an eye. With this new version of the Mental Logs, you can also perform a Clairvoyance experiment, by predicting the totals even before the numbers to be totaled are seen by you or the spectator. The spectator in fact throws the logs, assembles them together, and you immediately write a total down on a piece of paper.
The spectator then turns all the logs over, totaling the numbers that were hidden on their bottom sides. Naturally the total matches what you wrote on your slip of paper.
Nice trick, good price!