Scientific calculator with contextual history
Enter a whole expression, check its meaning and correct it without starting over. Recall earlier calculations with their original angle setting. No account, uploads or saved browser storage.
Calculate, inspect and reuse
Conventions at a glance
Precedence you can inspect
Start with (2+3)*sqrt(16)+2^3. Parentheses produce 5, the square root is 4 and the power is 8, so the result is 28. Correcting the first 3 to 4 gives 32. Powers group from the right: 2^3^2 means 2^(3^2)=512. A leading minus applies after a power, so -2^2=-4 but (-2)^2=4. Multiplication and division proceed left to right. Implicit multiplication has ordinary multiplication priority: 1/2 pi means (1/2)*pi; write 1/(2 pi) for the other meaning.
Angles and percentages are conventions
Select DEG before sin(30) to obtain approximately 0.5; choose RAD before sin(pi/2) to obtain 1. Inverse trig returns the selected unit too: asin(0.5) in DEG is approximately 30. The percent operator divides by 100, so 200+10%=200.1. For an increase use 200*(1+10%)=220. The context panel and copied summary preserve these rules. Switching angle mode previews a new interpretation but does not rewrite previous history.
Recall and correct with the original settings
Calculate sin(30) in DEG, then calculate sin(pi/2) in RAD. Recall the first history entry: DEG returns, with a visible announcement and the original expression. Edit it to sin(90) and calculate again to get 1. Clear entry leaves other work intact; clear history leaves the draft intact. Reset all or reload clears the temporary session. Nothing is shared through a URL or stored on the device.
Recognize numerical and notation limits
Use a decimal point and no grouping punctuation. Functions require parentheses: ln(e)=1 and cbrt(-8)=-2. The evaluator deliberately does not infer rational exponents in (-8)^(1/3), even though its real cube root exists; use cbrt(-8). sqrt(-1), ln(0), division by zero and recognized tangent singularities need a different real expression. Results are approximate; very small nonzero underflow is reported instead of shown as exact zero. Keep expressions within 1024 characters, 512 tokens and 64 nested levels.
How it works
Angle context travels with your calculation
Choose DEG for degrees or RAD for radians before using trig. sin(30) in DEG is approximately 0.5; the same input in RAD is different. Recalling history restores its original angle unit and announces the change.
Repair a draft without losing it
Enter the complete expression or use the caret-aware keys. Calculate stores a valid result; a specific error keeps the editable draft. Check the normalized expression and approximation notice before copying.
One useful example, no setup
The initial (2+3)*sqrt(16)+2^3 produces 28. Change 3 to 4 inside the first parentheses to get 32. Clear entry keeps history and angle mode; Reset all restores the example and DEG and clears history.
Common questions
Are these answers exact?
No. The evaluator uses finite binary 64 arithmetic, not rational or symbolic algebra. 0.1+0.2 displays 0.3 after 12 significant-digit formatting. Numbers beyond safe integer precision carry a warning; use an arbitrary-precision tool when every digit matters.
What happens to my history?
Only 20 valid calculations are kept in this page’s memory. Recall restores the expression and original angle setting. Clear history removes entries without changing your draft. Reset all or reloading clears the session; nothing is written to browser storage.
Are expressions sent or saved?
No. Calculation and history are local and ephemeral, with no input in URLs, logs, network requests or browser storage. Copy is an explicit action; the copied summary then belongs to your clipboard. No account is needed.
Why does sin(30) change in radians?
DEG treats 30 as degrees; RAD treats it as radians. DEG sin(30)≈0.5, while RAD sin(30)≈−0.988. Use RAD sin(pi/2)≈1. History recall restores the earlier unit rather than silently reusing the current one.
How do powers and negative signs work?
Powers associate right and come before a leading sign: -2^2=-4,(-2)^2=4 and 2^3^2=512. Use parentheses to make your intention explicit. For the real cube root of−8, use cbrt(-8); rational-exponent inference on a negative base is unsupported.
What does the percent key mean?
It always divides the preceding value by 100. Thus 200*10%=20 and 200+10%=200.1, not 220. To increase 200 by 10%, write 200*(1+10%). This scientific convention does not guess contextual pocket-calculator percentages.
Practical guides
- Expression conventions: powers, percentages and angle units
Worked examples explain how to enter, inspect and reuse real numerical expressions without losing angle or notation context.
Scope and limitations
Real numerical arithmetic only, not symbolic proof, graphing or professional advice. Binary 64 results are approximate, displayed with up to 12 significant digits. Input limits: 1024 characters, 512 tokens, 64 levels and 20 session history entries. No external data feed is required.