For words that only have three letters, there is absolutely no 4th letter. By way of example with the word “add”, there won't be any additional letters afterwards and so has to be the word "add". The word “addict” is during the BIP39 wordlist however, you would've employed “addi” for https://doctorbookmark.com/story18895250/5-simple-techniques-for-bip39-seed-phrase