The system is played on one of the dozens and either high (19 to 36) or low (1 to 18). The only numbers against you if you go high are zero and 13 to 18; or zero and 19 to 24 if you go low. Bet 20 units on the dozen and 30 on the ‘chances simples’. If the dozen wins you lose 30 on the chances simples but win 40 on the dozen. If chances simples wins you lose 20 on the dozen but win 30.
Martingale systems are based on a theory of doubling the stake plus a bit more every time you lose on an even-money chance. Be aware that should you bet just eight times without success your cumulative loss will already be 255 times your original stake. Here is one system which does offer a reasonable chance of success to small money gamblers. It was devised by one Jon Harris, apparently ‘an ardent student of gambling’.
If you are playing roulette you will soon be introduced to the Martingale system and/or its many variations. Beware. In theory it is an unbeatable system. In practice there will come a time when you are betting a huge amount in an effort to win a minuscule profit – always assuming you have enough money to stake and that the casino will accept the size of wager. The system is designed to cover 30 of the possible 37 numbers and make a ten-unit profit on each winning spin.