I took the index from the words, converted the range to binary, added three zeros, calculated the sha256 digest, took the 1st A part of the hexadecimal to transform it to binary, added 3 zeros into the eight digits from the binary and got 00000010011 which translates to 19 in https://yourbookmarklist.com/story19193688/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool