For words that only have 3 letters, there isn't any 4th letter. For instance with the word “insert”, there are no a lot more letters Later on and thus has to be the word "insert". The word “addict” is inside the BIP39 wordlist however you might have used “addi” for https://thebookmarkid.com/story18953681/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool