This method is a classical type of a double bet. 

Besides two required double bets, it also requires 
addition to the winnings. Because of this, the effect 
from the double bet is noticeably increased. 

The feature of this method is that it, as none the rest, 
gives a lot of possibilities for the individual development. 

You can make it the base of a big game, its structure 
allows to use it for a modest game with the profit expectations 
of 15-20 units too. 

The technology of the bet is following: three chosen chances 
play with bank simultaneously. Every time put one unit to 
the won one. This goes the following way: 

1st spin - place one unit, one unit is gained; 
2nd spin - place 2 plus 1 units, total three, 6 units are gained; 
3rd spin - place 6 plus 1, total 7, 14 units are gained. 

After this we start with the first bet again. Also after 
any intermediate loss place one unit on a respective chance 
again. Using this scheme play all three chosen chances 
simultaneously. 

If the loss of 20 or more units happens as a result of the 
game, all the bets should be doubled. If deterioration 
approaches again, the bets should be double again. Now, instead 
of one unit on each chance place four. After achievement of 
the above-zero condition we return to initial bets.