I took the index in the words, transformed the quantity to binary, additional three zeros, calculated the sha256 digest, took the 1st Portion of the hexadecimal to transform it to binary, added 3 zeros into the eight digits in the binary and bought 00000010011 which interprets to 19 in decimal. https://userbookmark.com/story19431668/5-essential-elements-for-bip39-explained