The Four Function Calculator handles addition, subtraction, multiplication, division, parentheses, and square roots in a single keypad. Enter a line, press equals, and reuse the last answer with ans when a problem needs a second step.
Calculate basic arithmetic online
The Four Function Calculator is built for everyday arithmetic that still needs order of operations. Digits, decimals, and the four operators share one entry row, so a homework check or a quick estimate does not require a scientific keypad. History keeps recent lines above the entry so a mistyped digit can be compared with the last result without rewriting the whole problem from scratch.
Clear, backspace, undo, and redo sit above the keypad for edits. Keyboard entry works beside click input, and Enter evaluates the current line the same way the equals key does.
Add, subtract, multiply and divide
The Four Function Calculator evaluates plus, minus, times, and divide with standard precedence, so 2+3×4 returns 14 rather than 20. Explicit parentheses override that order when a problem groups a sum first. Results use significant-figure aware formatting so float noise from values like 0.1+0.2 does not print as a long binary artifact.
Chained work stays on the entry row after equals, which makes a follow-up multiply or divide a short edit instead of a full retype.
Use parentheses and the square root
Parentheses group subexpressions before the surrounding operators run. The square root key inserts sqrt( so an expression like sqrt(9) evaluates to 3, and nested forms such as sqrt(16)+2 remain valid. When a root argument is negative in the reals, the calculator reports an undefined result instead of inventing a real number.
Mixing roots with the four operators is allowed on one line, which keeps multi-step radical arithmetic in a single evaluation.
Reuse the last answer
After a successful equals, the Four Function Calculator stores the value in ans. Pressing ans pastes that value into the next expression, so 7×8 followed by ans+4 yields 60 without copying digits by hand. Clearing the entry does not wipe ans until a new successful evaluation replaces it, which keeps a stable last result across short edits.
Undo and redo restore the entry text only; they do not roll back the stored ans value from a prior evaluation.
Frequently asked questions
How do I use the four function calculator?
Type or tap digits and operators into the entry row, then press equals or Enter. Use Clear to wipe the entry, Back to delete one character, and Undo or Redo to step through recent entry text.
Does it follow order of operations?
Yes. Multiplication and division run before addition and subtraction, and parentheses change that order. The expression 2+3×4 evaluates to 14.
How do I reuse my last answer?
Press ans after a successful equals. The calculator inserts the previous result into the new expression so chained calculations stay short.
Can it do square roots?
Yes. The √ key inserts sqrt(, and expressions such as sqrt(9) or 2+sqrt(16) evaluate through the shared math engine.
Is it free?
Yes. The Four Function Calculator on Quick Calculators is free to use in the browser with no account required.
Summary
The Four Function Calculator covers the four operators, parentheses, square roots, and answer reuse on a focused keypad. It is the lightest instrument in Math Tools and links forward to the Scientific Calculator when trig, logs, or factorials enter the problem.