For words that have only 3 letters, there is no 4th letter. For example with the word “add”, there are no extra letters afterwards and so must be the word "insert". The word “addict” is while in the BIP39 wordlist however , you would've used “addi” for “addict”. - Lưu https://socialdosa.com/story8685821/5-essential-elements-for-bip39-explained