I took the index of the words, converted the selection to binary, extra three zeros, calculated the sha256 digest, took the primary part of the hexadecimal to convert it to binary, included three zeros into the 8 digits with the binary and got 00000010011 which translates to 19 in decimal. https://bookmarkprobe.com/story19250855/the-definitive-guide-to-bip39-seed-phrase