I took the index of the words, converted the amount to binary, added three zeros, calculated the sha256 digest, took the primary Portion of the hexadecimal to transform it to binary, additional three zeros to your eight digits of your binary and got 00000010011 which translates to 19 in decimal. https://todaybookmarks.com/story18982699/top-guidelines-of-bip39-word-list-pdf