The 256 odù — the arithmetic of the corpus

Each leg of an odù is four marks, and each mark is one of two states, so a leg has 2^4 = 16 possibilities and a full odù, read as two legs, has 16 x 16 = 256. Sixteen of those are the meji, the 'doubles', where both legs are the same figure; the remaining 240 are the àmúlù, the combinations of two different figures. Every one of the 256 is an odù with its own verses, and a babalawo is expected to be able to move within all of them, which is why the training is measured in decades.