A full keyboard-driven calculator like the Windows one: memory, history, percent and square root, in its own window or as an installed app.
M
History
Use it as a stand-alone app
To install: use the browser menu, "Install app" or "Add to home screen". It then works offline.
Keyboard: digits and operators, Enter for the result, Esc to clear, Backspace to delete.
Formula
Standard mode keeps one running total and one pending operator. When you press the next operator, the pending one is applied to the total and the entry:
tn+1=tn□xn(□∈{+,−,×,÷})
The percent key changes the entry before the pending operator uses it: after plus or minus the entry becomes t⋅x/100, after times or divide it becomes x/100. Square root, square and reciprocal act on the number on the display straight away.
Worked example
You want 15 % tip on a 48.50 bill, added to the bill.
Type 48.50, then +.
Type 15, then %. The display shows 7.275, which is 15 % of 48.50.
Press =. The total is 55.775.
Press = again and the calculator repeats the last step and adds 7.275 once more. That repeat feature is also handy for compound growth: 1000 × 1.05 = = = applies the 5 % rise three times.
Common mistakes
Expecting the order of operations. Standard mode is strictly left to right. For an expression such as 2 + 3 × 4 use the scientific calculator.
Pressing % and expecting a separate result. It rewrites the entry first; press = afterwards.
Dividing by zero. The display shows an error, and the next digit starts a clean calculation.
Reading rounded results as exact. The display holds up to 15 significant digits, and tiny binary rounding noise such as 0.1 + 0.2 is cleaned to 0.3.
Frequently asked questions
Why does 2 + 3 × 4 give 20 here and 14 on a scientific calculator?
Standard mode works the way pocket calculators and the Windows Standard calculator do: each operator is applied as soon as you press the next one, from left to right. (2 + 3) × 4 is 20. The scientific and engineering calculators follow the usual order of operations, so multiplication comes first and the answer is 14.
What does the % key do?
It depends on the operator before it. After + or − it takes that percentage of the first number, so 200 + 10 % adds 20 and the result is 220. After × or ÷ it simply divides the entry by 100, so 50 × 10 % is 5.
How do I use it like a Windows app, outside the browser tab?
Press "Open in its own window" for a small separate window, or use "Install as an app" (or the browser menu, Install app) to get an icon on your desktop or phone. Once installed it works without an internet connection.
Can I type on the keyboard?
Yes. Digits and + − * / work directly, Enter or = gives the result, Backspace deletes a digit, Delete clears the entry, Esc clears everything, % is percent, R is 1/x, Q is x squared and @ is the square root. Ctrl+C copies the displayed number.