For words that only have 3 letters, there's no 4th letter. As an example with the word “include”, there aren't any additional letters afterwards and thus must be the word "increase". The word “addict” is in the BIP39 wordlist however, you might have employed “addi” for “addict”. Artwork is really https://mysocialfeeder.com/story4343602/a-secret-weapon-for-bip39-words-to-numbers