I took the index with the words, transformed the quantity to binary, additional 3 zeros, calculated the sha256 digest, took the first A part of the hexadecimal to convert it to binary, added three zeros towards the 8 digits of the binary and got 00000010011 which translates to 19 in https://bookmarkinglive.com/story19664451/getting-my-bip39-words-to-numbers-to-work