I took the index of the words, converted the range to binary, extra a few zeros, calculated the sha256 digest, took the 1st Section of the hexadecimal to transform it to binary, extra 3 zeros to the eight digits in the binary and got 00000010011 which translates to 19 in https://agency-social.com/story4605821/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool