I took the index of the words, transformed the selection to binary, included 3 zeros, calculated the sha256 digest, took the very first Component of the hexadecimal to transform it to binary, added a few zeros for the 8 digits with the binary and got 00000010011 which translates to 19 https://iowa-bookmarks.com/story14452066/bip39-seed-phrase-mnemonics-generator-an-overview