I took the index on the words, transformed the range to binary, included a few zeros, calculated the sha256 digest, took the primary Element of the hexadecimal to convert it to binary, added three zeros for the eight digits in the binary and got 00000010011 which translates to 19 in https://my-social-box.com/story4193955/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool