I took the index with the words, transformed the number to binary, additional 3 zeros, calculated the sha256 digest, took the main A part of the hexadecimal to transform it to binary, added a few zeros into the 8 digits from the binary and bought 00000010011 which translates to 19 https://mnobookmarks.com/story18762403/not-known-factual-statements-about-bip39-explained