I took the index in the words, converted the quantity to binary, additional three zeros, calculated the sha256 digest, took the main Element of the hexadecimal to convert it to binary, included three zeros for the 8 digits in the binary and bought 00000010011 which translates to 19 in decimal. https://lingeriebookmark.com/story8618779/not-known-factual-statements-about-bip39-explained