I took the index of the words, converted the selection to binary, additional a few zeros, calculated the sha256 digest, took the 1st part of the hexadecimal to convert it to binary, extra three zeros for the 8 digits of the binary and acquired 00000010011 which translates to 19 in https://7prbookmarks.com/story19499214/fascination-about-invalid-bip39-phrase