I took the index with the words, transformed the amount to binary, additional three zeros, calculated the sha256 digest, took the main Section of the hexadecimal to transform it to binary, extra 3 zeros towards the 8 digits of the binary and received 00000010011 which translates to 19 in decimal. https://bookmarkprobe.com/story19287226/not-known-facts-about-bip39-english-words