I took the index in the words, converted the number to binary, included three zeros, calculated the sha256 digest, took the main A part of the hexadecimal to convert it to binary, included 3 zeros towards the 8 digits of the binary and got 00000010011 which translates to 19 in https://socialmediainuk.com/story20875390/top-guidelines-of-bip39-word-list-pdf