I took the index in the words, converted the range to binary, additional a few zeros, calculated the sha256 digest, took the primary A part of the hexadecimal to transform it to binary, added three zeros into the eight digits in the binary and bought 00000010011 which translates to 19 https://www.storeboard.com/blogs/beauty-and-fashion/opening-the-globe-of-bip39-a-comprehensive-guide-to-mnemonic-expressions-and-word-checklists/6026188