A function takes each input from its domain and gives back exactly one output, and the outputs make the range. Function notation names the rule and the input together: f(3) = 11 says that 3 goes in and 11 comes out. The domain follows the situation, so the cart runs only from 0 to 6 seconds and cups come in whole numbers. A table, a diagram or a graph is a function only if no input has two outputs.