I took the index of the words, converted the quantity to binary, added 3 zeros, calculated the sha256 digest, took the 1st part of the hexadecimal to convert it to binary, included 3 zeros for the eight digits of the binary and got 00000010011 which translates to 19 in decimal. https://bookmarkity.com/story19226883/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool