For words that only have three letters, there's no 4th letter. By way of example with the word “include”, there won't be any extra letters afterwards and therefore has to be the word "include". The word “addict” is in the BIP39 wordlist however , you would have applied “addi” for https://getsocialselling.com/story4251383/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool