I took the index in the words, converted the amount to binary, additional three zeros, calculated the sha256 digest, took the main part of the hexadecimal to transform it to binary, additional 3 zeros into the eight digits of the binary and acquired 00000010011 which translates to 19 in decimal. https://ragingbookmarks.com/story18804460/invalid-bip39-phrase-things-to-know-before-you-buy