Martingale

The Martingale System is an oft-heralded means of winning at roulette or blackjack by simply doubling every losing bet until you win.

http://wizardofodds.com/ask-the-wizard/betting-systems/martingale/

https://en.wikipedia.org/wiki/Martingale_(probability_theory)#Examples_of_martingales

In reality you’ll hit the table limits pretty quickly. Even if you don’t, you’ll bankrupt yourself without too much difficulty.

In bookie bashing, however, Martingaling is a great way of clearing a low value, low wagering offer. EG a Blackjack offer of “buy in with 5 for 5, with £100 wagering requirement”

Start with a £10 stake, and if you win keep doubling your stake until you’re either bust or you’ve cleared the WR. Its the fastest strategy, and the most fun. In the above example you only need 3-4 hands, depending on doubling/splitting

Hand 1 £10 – win
Hand 2 £20 – win
Hand 3 £40 – win
Hand 4 £30 (no need to bet anymore to clear the WR) – win

A £5 bonus turns into £140 – Odds on this happening are 16/1.