Click on (or tap) the poker chips to turn them over.

Drag the poker chips to mix them up.

STEP #1
The Magician asks the Spectator to mix the poker chips and place them on table in two rows, with three poker chips in each row:
 5   2   9 
 1   8  10

The Magician must remember the position of the yellow chips.
(In the example above, top row: chips in positions 1^st and 3^rd and bottom row: chips in position 2^nd and 3^rd.)

STEP #2
The Magician turns their back and instructs the Spectator to turn over any 3 chips.
(In this example we will assume top row: chips in positions 1^st and 3^rd and bottom row: chip in position 2^nd are turned over.)
 0   2   4 
 1   3  10

STEP #3
With back still turned the Magician must now recall the position of the yellow chips as they were in step #1, and ask the Spectator to turn them over.
(In this example the Magician asks for chips in positions 1^st and 3^rd in top row to be turned over and chips in positions 2^nd and 3^rd in bottom row to be turned over) resulting in:
 5   2   9 
 1   8   5 

STEP #4
In the last step the Spectator turns over any 3 chips and covers them with a playing card so the number cannot be seen.
(In this example the Spectator turns over and covers chips in positions 1^st and 2^nd in top row, and chip in position 1^st in bottom row.)
 0   7   9 
 6   8   5 

At this point the Magician turns around and gives the sum of 3 the hidden chips.

SECRET
In her/his head the Magician calculates:

Y = # yellow chips showing; in this case 2 (9 and 8)

S = sum of exposed chips; 22 in this case (9 + 8 + 5)

Uses this formula to calculate the sum of the 3 hidden chips:

(10*Y + 15) - S

In this example (10*2 + 15) - 22 = 13
which is the sum of the hidden chips (0 + 7 + 6)

Click Me To Hide Instructions Before Performance