In Excel, I have a list of 30 different numbers ranging from $100$ to $1000$. If I have a sum representing several of those variable numbers, is there a way for me to determine which possible combinations of those variable numbers total together to equal that sum?
This is called the subset sum problem which is a type of knapsack problem. Not very easy to solve. For exact answers we only know exponential algorithms meaning it'll take a while for you to get your answers. If you want faster algorithms then they will only give you approximations.