For words that only have 3 letters, there's no 4th letter. Such as with the word “include”, there isn't any extra letters Later on and thus should be the word "incorporate". The word “addict” is from the BIP39 wordlist however, you would have applied “addi” for “addict”. This extra complexity https://bookmarkplaces.com/story18893851/getting-my-bip39-words-to-numbers-to-work