For words that have only 3 letters, there's no 4th letter. One example is with the word “include”, there are no additional letters afterwards and so have to be the word "incorporate". The word “addict” is within the BIP39 wordlist however , you might have made use of “addi” for https://thesocialroi.com/story8609296/getting-my-bip39-words-to-numbers-to-work