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### D'Alembert system

D'Alembert system is called after a 18th century French physician Jean le Rond d'Alembert. This system is based on the basic belief that in the long run two events of approximately equal probability will happen roughly the same number of times. You must add or subtract the established basic unit to the stake depending on the result of previous event. The stake should be decreasing after the winning bet and increasing after the loosing one.

The difference between D'Alembert and Martingale system is that you do not have to double your betting money in the case of lose - so your stakes do not grow so rapidly.

Example:
* You bet 1 USD and you win (the stake remains the same)
* You bet 1 USD and you lose (the stake increases)
* You bet 2 USD and you lose (the stake increases)
* You bet 3 USD and you lose (the stake increases)
* You bet 4 USD and you win (the stake decreases)
* You bet 3 USD and you lose (the stake increases)

and so on.

Parlay system - the system of a positive progression
Parlay System is a positive progression system similar to the Paroli System. It is also known as the "Let It Ride" system. It is one of the oldest and the simplest betting systems. It is based on pyramiding your profit. You use your original stake and your winning profit (or some part of it) to place then next bet with (of course only in the case of winning the first bet).

Example:
You bet 1 USD. You win 2 USD.
You bet 2 USD. You win 4 USD.
You bet 4 USD. You win 8 USD.

And so on...