As a senior citizen this might seem like an obvious question but I would like to know how to add, subtract, multiply, and divide whole numbers which involve both POSITIVE and NEGATIVE numbers in any combination using both a basic and scientific calculator. I have a TI30 that has a key to MINUS sign to be attached to any number as you enter it. The answer is then correct. The basic calculator has no such key. Does this mean that these calcs cannot perform using MINUS numbers even if there is a way to assign a (-) sign? If there is how do I do it? I ask because the TI is more than I need for basic math. I also have a CONTRACTORS calc that does fractions, conversions, board feet, and much more. I rarely use it. All help welcome. A simple answer will suffice. If I need to use the TI for that, then that is acceptable.