I took the index of your words, transformed the range to binary, extra a few zeros, calculated the sha256 digest, took the first Portion of the hexadecimal to transform it to binary, included 3 zeros into the eight digits of your binary and acquired 00000010011 which interprets to 19 in https://bookmarklogin.com/story18919263/a-secret-weapon-for-bip39-words-to-numbers