I like to do subtraction in an algorithm, but is kinda hard to do an algorithm on a computor......
the answer is 189 but im not really sure how to show my work....
I guss you just subtract each of the colums that are spaced out and if you cant just carry from the next colum and you start from the right and move to the left once you have sutracted all the colums you should have your answer!
2 0 2 1
-1 8 2 3