Pip install bip39 https://telegra.ph/Producing-Custom-Bitcoin-Addresses-A-Take-A-Look-At-BIP39-Strategies-06-28 3a43fced052690635cc9fdce418514528b000dff3eaa5b986ea7be809062e775f2fe99c76733ff200b56fb70cac7c6ac7818b1e8139192a70fe274f5bf57fa46 For words that only have three letters, there isn't any 4th letter. One example is Using the word “add”, there are no more letters Later on and so... https://bookmarkspring.com/story15716830/bip39-longest-word-bip39-checksum-an-overview-https-cutt-ly-uryc5rw7