The d'Alembert system is very simple and relatively thrifty. It bears the name of the French mathematician, physicist and philosopher Jean le Rond d'Alembert (1717–1783).
The principle of the d'Alembert strategy consists in betting on red or black numbers in Roulette. Again it is possible to bet on any other even-money bets (high/low, even/odd numbers) with the payout 1:1.
Start with betting one unit (1$, 10$, ...) on your favorite color in Roulette. If you win in the first spin, then the "sequel" ends and you start all over with one unit. If you lose, bet an extra unit in the next round. If you win, your next bet will be lower than your last bet by one unit. It means that if you are successful then you can win a higher bet and if you are unlucky then you lose a lower amount.
|Bet Amount||Outcome of the Bet||Profit/Loss||Cumulated Profit/Loss||Next Bet (Loss +1, Win -1)|
|1 unit||win||2||+18||The sequel ends, start over with 1 unit.|
The strategy of d'Alembert is very profitable if you catch a good sequel. Of course the opposite situation can occur as well. Nevertheless the d'Alembert's strategy is very economical, so it is very unlikely and unlucky to ruin your capital quickly – which could happen if you used e.g. the Martingale strategy, when the bets are doubled after each lost spin.