I took the index on the words, transformed the number to binary, added three zeros, calculated the sha256 digest, took the 1st Portion of the hexadecimal to transform it to binary, additional three zeros to your eight digits in the binary and acquired 00000010011 which translates to 19 in decimal. https://socialfactories.com/story4366970/a-review-of-bip39-passphrase