When I was working as a Cashier Supervisor, one of my responsibilities was to count the cash into the safe on a regular basis. The process was taking too long and it had a big margin for human error. As a tech-savvy person, I wanted to create something to make my job easier and I came up with this super simple safe calculator using only * and SUM. My goal was to optimize the process of counting the cash in the safe not only for my sake but for my colleagues who weren’t tech-savvy. The result of this easy solution was the following: The counting time became much less since all the calculations were made automatically by the spreadsheet. The counter had to provide just the number of bank notes or cash bags. The human – error was eliminated too since now the counter didn’t have to calculate the sum with the calculator, instead, the spreadsheet did all the calculations automatically free from human error. It was simple; yet, very effective optimization solution.