The Labouchere is another highly favoured betting system. You take a sequence of numbers, for example 10, 20, 30, 40, 50, with each number representing betting units. You add the first and the last number to form your bet, so for this example you'd bet 60 units. In the event that you lose you add the bet to the end of that row of numbers, so now we're working with 10, 20, 30, 40, 50 and 60. If you win your next bet (10+60) for 70 units you'll get ahead by 10.
After winning, you'll remove the numbers you just bet from your sequence, so in this instance you would subtract the 10 and the 60, making your new row 20, 30, 40, 50.
If you manage to get to a point where you have just one number in your row and that bet wins, you've won your sequence.
This method is not dissimilar to the Martingale method.