Originally, martingale referred to a class of betting strategies popular in 18th century France. The simplest of these strategies was designed for a game in which the gambler wins his stake if a coin comes up heads and loses it if the coin comes up tails. The strategy had the gambler double his bet after every loss, so that the first win would recover all previous losses plus win a profit equal to the original stake. Since a gambler with infinite wealth is guaranteed to eventually flip heads, the martingale betting strategy was seen as a sure thing by those who practiced it. Unfortunately, none of these practitioners in fact possessed infinite wealth, and the exponential growth of the bets would quickly bankrupt those foolish enough to use the martingale after even a moderately long run of bad luck.
The martingale roulette system theoretically allows you to win 10% at roulette nine out of ten times. The tenth time (on average) you will lose everything.
You start with 100 chips and must always place your bet on red/black or odds/evens.
Let's suppose your first bet is 10.
If you do not win bet 20. If you win you get 20 chips.10 to "refund" the 10 lost and 10 your winnings. Again cash your chips and leave.
You do this until either you win or all your chips are finished. Do not play after you have got your win. Statistically you must play a minimum as the odds are against you.
If you go to the casino you will at least had the fun of winning 9 out of 10 times. The casino will in the end will have the upper hand as the 0 and 00 are against you. If 100 people use this system 86 will win their 10% which is "payed" for by 10 others.4 will lose and "subsidise" the casino.With any other system you risk losing much more and there is little chance that you will ever win.
Do notice however that in real life casinos avert the Martingale systems by imposing upper table limits.