For words that only have three letters, there is absolutely no 4th letter. As an example with the word “include”, there won't be any extra letters afterwards and so must be the word "insert". The word “addict” is inside the BIP39 wordlist however , you would have utilized “addi” for https://brightbookmarks.com/story18998420/5-simple-techniques-for-bip39-word-list-pdf