So a mathematical operation can be represented as a function that maps inputs to outputs. For example "sin(**x**)" is a function that maps 1 input to 1 output, and "**a** + **b**" maps 2 inputs to 1 output. My question is is there a function that requires a minimum of 3 inputs on a fundamental level? I'm not talking about something like "**a** + **b** + **c**" even though that has 3 inputs because the steps of solving that function are evaluated 2 variables at a time ie "(**a** + **b**) + **c**". Is there something that **needs** 3 or more inputs to make sense in the same way addition needs 2? I don't have very strong math background so I didn't know how to google my question properly or how to tag it here properly. Thank you for your patience.