= does the same and starts a fresh entry. Divide-by-zero and overflow show Error. The % key treats the current entry as a percentage of the accumulated value.
This works like a standard four-function calculator: it holds one accumulated value and one pending operator at a time. Pressing another operator evaluates the pending pair first, then starts a new pending operation; pressing equals does the same and locks in the result.
The percent key follows the convention most people expect from everyday mental math rather than treating the number as a standalone percentage: pressing % after an operator applies it to the accumulated value. For example, with 200 on screen and + 10% pressed, the calculator adds 10% of 200 (20) — the same way you'd figure out a tip or a markup by hand.
Divide-by-zero and results too large to display both show Error rather than a wrong number, and the full keyboard works too — number keys, + - * /, Enter or = for equals, Escape to clear, and Backspace to remove the last digit.
Yes — number keys, the four operators (+, -, *, /), Enter or = for equals, Escape to clear everything, and Backspace to delete the last digit typed.
It applies a percentage of the accumulated value rather than treating the on-screen number as a standalone percent — so 200 + 10% adds 20 (10% of 200), matching how most people calculate a tip or markup by hand.
The display shows Error instead of an incorrect result. The same happens if a calculation produces a number too large to display.
Yes, but each operator evaluates the pending pair in the order you press it, left to right — pressing + then 3 then × evaluates 5 + 3 first (giving 8), then multiplies by 2, rather than following algebraic order of operations. This matches how basic pocket calculators work, not scientific ones.