The KO Count, or the Knockout Count, was popularized in the book Knockout Blackjack by Ken Fuchs and Olaf Vancura. This is an example of an unbalanced card counting system, because the total number of -1's and +1's in the deck don't balance to 0 when you count through an entire deck.
The KO Blackjack card counting system was designed to be simple to use and also eliminate the need to calculate a true count from the running count.
The point values are distributed as per the table below:
2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | A |
+1 | +1 | +1 | +1 | +1 | +1 | 0 | 0 | -1 | -1 |
The Knockout Count is almost identical to the Hi-Lo count except the 7's are included as +1's in the KO count. The number of decks in play determine the starting number for the count.