THOMAS ELROD SYSTEM 

Basically, the system uses a debit, or due column, 
and a control number which is divided into the debit 
to arrive at the figure of the amount of the next bet. 

Elrod used a basic goal of 100 units for his initial 
debit or due. He used the figure 20 as his initial 
control number. 

He divided 100 by 20 and therefore his first bet was 
5 units. 

If he lost, he added the amount of the losing bet to 
the debit and divided again. After a win, he subtracted 
the amount of odds he control figure and the amount of 
units won from the debit figure and divided again. 

Elrod used the column or dozens exclusively, thus his 
odds were always 2 to 1 and this was always the figure 
he would subtract from the control number after a win. 

He never allowed his control number to drop below 3. 
Thus, he needed two or three wins in a row at the end 
of a series in order to close it out and start over. 
He also never reduced his bets at any time. 

Here is an example: 

Debit Control Bet Outcome Win Lose TWin TLose 
100    20     5      L     0   5    0    5 
105    20     5      L     0   5    0   10 
110    20     5      W    10   0   10   10 
100    18     5      L     0   5   10   15 
105    18     5      L     0   5   10   20 
110    18     6      W    12   0   22   20
98     16     6      L     0   6   22   26 
102    16     6      L     0   6   22   32 
108    16     6      W    12   0   34   32 
92     14     6      W    12   0   46   32 
80     12     6      L     0   6   46   38 
86     12     7      L     0   7   46   45 
93     13     7      W    14   0   60   45 
79     11     7      W    14   0   74   45 
65     9      7      L     0   7   74   52 
72     9      8      L     0   8   74   59 
81     9      9      L     0   9   74   68 
90     9     10      L     0  10   74   78 
100    9     10      W    20   0   94   78 
80     7     11      W    22   0  106   78 
56     5     11      L     0  11  106   89 
67     5     13      L     0  13  106   99 
80     5     16      L     0  16  106  115 
96     5     19      L     0  19  106  134 
115    5     23      W    46   0  152  134
69     3     23      L     0  23  152  157 
92     3     30      L     0  30  152  187 
122    3     40      W    80   0  192  187 
42     3     40      W    80   0  272  187
0 

Here you start over. Obviously there are endless variations. 
You don't have to use dozens or columns. You can arbitrarily 
add numbers to either the debit or control numbers to 
reduce the amount of your bet. And, you can adapt the system 
to other games and types of gambling. 

Obviously, the system is not foolproof. Bets will eventually 
rise during losing streaks. Sometimes they can get prohibitively 
big. Still, with a little common sense it's not too bad.