I took the index of the words, transformed the variety to binary, included 3 zeros, calculated the sha256 digest, took the first Portion of the hexadecimal to convert it to binary, included three zeros to your 8 digits in the binary and bought 00000010011 which translates to 19 in decimal. https://7bookmarks.com/story18867579/invalid-bip39-phrase-things-to-know-before-you-buy