Mathematically it can vary if addition/subtraction. If it's multiplication/division, then it's always negative.
Because mathematically it's the inverse operation, the same way that subtraction is the "opposite" (inverse operation) of addition.
who discovered addition and subtraction.
Addition is the inverse operation to subtraction.
Addition and subtraction are reverse operations.
definiton of addition and subtraction
They are on the same level as each other. Mathematically, addition and subtraction have equal precedence and are done in a left to right order. Microsoft Excel is designed to follow the rules of mathematics, so they have equal precedence.
Subtraction can be seen as the inverse operation to addition.
Addition and subtraction are inverse functions.
You don't. You can check addition with subtraction or subtraction with addition, since subtraction is the opposite of addition. Similary, you can check division with multiplication, or vice versa.
Addition is a sum and so is subtraction. So there's your answer!