I took the index on the words, converted the range to binary, additional a few zeros, calculated the sha256 digest, took the first part of the hexadecimal to transform it to binary, extra a few zeros into the eight digits in the binary and obtained 00000010011 which translates to 19 https://businessbookmark.com/story4223884/bip39-seed-phrase-mnemonics-generator-an-overview