I took the index in the words, converted the selection to binary, included a few zeros, calculated the sha256 digest, took the primary Section of the hexadecimal to transform it to binary, added 3 zeros to the 8 digits on the binary and received 00000010011 which interprets to 19 in https://naturalbookmarks.com/story19001319/the-definitive-guide-to-bip39-seed-phrase