I took the index with the words, transformed the amount to binary, extra a few zeros, calculated the sha256 digest, took the first Component of the hexadecimal to transform it to binary, extra a few zeros to your eight digits of your binary and bought 00000010011 which interprets to 19 https://ztndz.com/story21942266/considerations-to-know-about-bip39-word-list-pdf