I took the index with the words, transformed the quantity to binary, included 3 zeros, calculated the sha256 digest, took the first part of the hexadecimal to transform it to binary, additional a few zeros for the 8 digits on the binary and got 00000010011 which interprets to 19 in https://easiestbookmarks.com/story19106781/not-known-facts-about-bip39-english-words