A tip becomes a pattern of electrical states
When you enter a percentage, the calculator’s software first represents the numbers in a form its processor can work with. Inside the chip, tiny transistors act as controllable switches: they change whether electrical signals count as one state or another. Groups of transistors form logic gates, which combine those states to carry out arithmetic.
A tip calculation may look like one operation on the screen, but the processor handles it as a sequence of smaller steps. It can multiply the bill by the tip rate, then add the result to the bill. The same kinds of switching circuits support those steps whether the displayed answer is a few digits or part of a plotted curve.
More features, same underlying work
A graphing calculator adds capabilities such as more memory, a larger display, and software for storing equations and drawing graphs. Those features make it more capable than a basic pocket calculator, but they do not replace the underlying logic. Its processor still relies on circuits that manipulate electrical states to perform calculations.
The useful distinction is between the task a calculator presents and the machinery that carries it out. “Calculate a tip” is a convenient instruction for a person; inside the device, it becomes a sequence of elementary operations. A graphing calculator can make that machinery feel far removed from everyday arithmetic, but the same basic switching principle lets it handle both.
