I took the index of the words, converted the number to binary, added 3 zeros, calculated the sha256 digest, took the primary Element of the hexadecimal to transform it to binary, included a few zeros to your 8 digits in the binary and acquired 00000010011 which interprets to 19 in https://tinybookmarks.com/story19131447/the-basic-principles-of-bip39-passphrase-generator