This is known as the cancellation system. Pick a series of numbers, say 1,2,3,4,5. Your first bet is the total of the two numbers on the end, or 6 units in this case. If you lose it, you cancel out the 1 and the 5, add the six to the end of the series and bet the 6 and the 2, for a total of eight units bet. Lose that one and you add the eight to the series, cancel the 2 and the six and bet a total of 11 (3+8) and so on. If you win, you proceed to the inside numbers until they are all cancelled out. Again, a loser, but an insidious one.

Soldiers in the Roman Legions used to shave down pig knuckles into the shapes of cubes, and toss them onto their inverted shields as a form of entertainment while in camp. Hence we get the term "to roll the bones". We do know that the game we know today as "craps" came to the United States from Europe.