I took the index of your words, converted the amount to binary, included three zeros, calculated the sha256 digest, took the main Portion of the hexadecimal to convert it to binary, extra 3 zeros into the 8 digits of the binary and acquired 00000010011 which interprets to 19 in decimal. https://echobookmarks.com/story18886424/the-2-minute-rule-for-bip39-all-words