Bip39 docs https://collinmmss433.lucialpiazzale.com/from-concept-to-fact-generating-bitcoin-addresses-with-bip39 Checksum generation: A checksum is generated from this entropy employing SHA-256 hashing, which allows verify the mnemonic's integrity afterwards. For words that only have 3 letters, there's no 4th letter. By way of example Along with the word “incorporate”, there won't be ... http://www.mediafire.com/file/uilrjfajg2ami24/pdf-14673-57158.pdf