i know [:-1] this method use remove the last digit,but i need mathematically steps like + - * /

why i am post this topic  mathbehind crack ecdsa

example input:
9cbdfb599ed0100
ce5efdaccf68080
1cbdfb599ed0100
397bf6b33da0200

i need output:
9cbdfb599ed010
ce5efdaccf6808
1cbdfb599ed010
397bf6b33da020
solve the math write here... :Note only last digits remove #mybadandgoodenglish