I took the index with the words, transformed the range to binary, included 3 zeros, calculated the sha256 digest, took the 1st part of the hexadecimal to transform it to binary, extra 3 zeros on the 8 digits in the binary and got 00000010011 which translates to 19 in decimal. https://esocialmall.com/story4346969/detailed-notes-on-copyright-wallet-seed-phrase-out-of-bip39