For words that only have 3 letters, there's no 4th letter. As an example with the word “insert”, there won't be any a lot more letters Later on and so have to be the word "insert". The word “addict” is from the BIP39 wordlist however, you might have utilized “addi” https://www.mediafire.com/file/qad32ryob76naol/pdf-7033-8222.pdf/file