For words that have only 3 letters, there isn't any 4th letter. For instance with the word “include”, there won't be any a lot more letters Later on and therefore needs to be the word "include". The word “addict” is inside the BIP39 wordlist however , you would've used “addi” https://bookmarkquotes.com/story19713237/getting-my-bip39-words-to-numbers-to-work