I took the index with the words, converted the range to binary, additional three zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to transform it to binary, additional a few zeros for the eight digits on the binary and got 00000010011 which interprets to 19 https://wiishlist.com/story19437704/5-simple-techniques-for-bip39-word-list-pdf