I took the index with the words, transformed the selection to binary, extra 3 zeros, calculated the sha256 digest, took the 1st part of the hexadecimal to transform it to binary, extra three zeros to your eight digits in the binary and obtained 00000010011 which interprets to 19 in decimal. https://enrollbookmarks.com/story18780641/helping-the-others-realize-the-advantages-of-bip39-seed-phrase-mnemonics-generator