Part III: Business & Regulation · Gambling Mathematics & Probability

29. Illustrious 18

Blackjack Math

The Illustrious 18 is a set of 18 playing deviations from basic strategy identified by mathematician Donald Schlesinger as the most profitable and important index plays for card counters using the Hi-Lo system. These deviations are triggered at specific true count thresholds and collectively account for approximately 80% of the expected value gained from playing deviations (as opposed to bet variation). Examples include standing on 16 vs. dealer 10 at true count 0 or higher (instead of hitting per basic strategy), and taking insurance at true count +3 or higher. Memorizing just these 18 deviations provides nearly all the benefit of a full deviation chart while being practical to learn. Surveillance personnel should recognize that players consistently making correct deviations at specific counts are almost certainly counting cards.

In practice

The “Fab 4” surrender deviations are often taught alongside the Illustrious 18: surrender 14 vs. 10 at true count +3, 15 vs. 10 at true count 0, 15 vs. 9 at true count +2, and 15 vs. Ace at true count +1. Together with the Illustrious 18, these cover the most critical surrender decisions.

One entry from the Casino Industry Glossary — 1,157 terms written for surveillance, compliance and operations professionals rather than for players. Definitions describe industry usage; where a term carries a regulatory meaning, verify against the instrument that governs your jurisdiction.