I took the index from the words, converted the selection to binary, included 3 zeros, calculated the sha256 digest, took the main A part of the hexadecimal to transform it to binary, added 3 zeros to the eight digits with the binary and obtained 00000010011 which interprets to 19 in http://edgargvkh682.theburnward.com/from-mnemonics-to-security-understanding-bip39-passphrases-and-their-importance-in-copyright