Using the Calculator
Click the keys or type directly on your keyboard — digits, + − * / ^ ( ), Enter to evaluate, Backspace to delete and Escape to clear. The expression builds up on the display, so you can see and correct the whole calculation before evaluating it, rather than working one operation at a time.
The Deg/Rad key switches the angle mode for all trigonometric functions. The current mode is always shown under the display; forgetting to check it is the single most common source of wrong trigonometric answers.
Order of Operations
The calculator evaluates a full expression using standard precedence rather than left to right, so 2 + 3 × 4 gives 14, not 20.
| Priority | Operation | Associativity |
|---|---|---|
| 1 (highest) | Parentheses and functions | Innermost first |
| 2 | Factorial, powers, roots | Right to left |
| 3 | Unary minus | Right to left |
| 4 | Multiplication, division | Left to right |
| 5 (lowest) | Addition, subtraction | Left to right |
Right associativity of exponents matters: 2^3^2 is 2(32) = 512, not (23)2 = 64. Use parentheses whenever the intent could be read either way.
Function Reference
| Key | Function | Notes |
|---|---|---|
| sin, cos, tan | Trigonometric functions | Respect the Deg/Rad setting |
| sin⁻¹, cos⁻¹, tan⁻¹ | Inverse trigonometric | Input must be in [−1, 1] for arcsin and arccos |
| ln | Natural logarithm, base e | Undefined for zero and negatives |
| log | Common logarithm, base 10 | Undefined for zero and negatives |
| ex, 10x | Exponentials | Inverses of ln and log |
| x2, x3, xy | Powers | xy accepts fractional and negative exponents |
| √, ∛, y√x | Square, cube and nth roots | Cube roots of negatives are supported |
| n! | Factorial | Whole numbers 0–170; above that the result overflows |
| 1/x | Reciprocal | Undefined at zero |
| % | Percent | a % b computes a × b ÷ 100 |
| EXP | Scientific notation | 3 EXP 8 means 3 × 108 |
| π, e | Constants | 3.14159265… and 2.71828182… |
| Ans | Previous answer | Chains calculations together |
| M+, M−, MR, MC | Memory | Add to, subtract from, recall and clear |
| RND | Random number | Uniform between 0 and 1 |
Degrees and Radians
Degrees divide a full turn into 360 parts; radians measure the arc length on a unit circle, so a full turn is 2π. Radians are the natural unit in calculus — the derivative of sin(x) is cos(x) only when x is in radians — while degrees dominate in surveying, navigation and everyday geometry.
radians = degrees × π ÷ 180 degrees = radians × 180 ÷ π
| Degrees | Radians | sin | cos | tan |
|---|---|---|---|---|
| 0° | 0 | 0 | 1 | 0 |
| 30° | π/6 | 0.5 | 0.8660 | 0.5774 |
| 45° | π/4 | 0.7071 | 0.7071 | 1 |
| 60° | π/3 | 0.8660 | 0.5 | 1.7321 |
| 90° | π/2 | 1 | 0 | undefined |
| 180° | π | 0 | −1 | 0 |
| 270° | 3π/2 | −1 | 0 | undefined |
| 360° | 2π | 0 | 1 | 0 |
Logarithm Rules
| Rule | Form |
|---|---|
| Product | log(ab) = log(a) + log(b) |
| Quotient | log(a/b) = log(a) − log(b) |
| Power | log(an) = n × log(a) |
| Change of base | logb(x) = ln(x) ÷ ln(b) |
| Identity | log(1) = 0, and logb(b) = 1 |
The change-of-base rule is how you compute a logarithm in any base with only ln and log available. For log2(64), enter ln(64) / ln(2) to get 6.
Floating-Point Accuracy
Like every calculator built on binary floating point, this one carries about 15–17 significant decimal digits. Some decimal fractions have no exact binary representation, which is why 0.1 + 0.2 can display as 0.30000000000000004 in a raw environment. Results here are rounded to 12 significant digits before display, which hides the artefact without materially affecting accuracy.
Very large and very small results switch automatically to scientific notation, and factorials above 170! exceed the maximum representable value and return infinity.
Privacy
Every calculation runs in your browser. Nothing is sent to a server, logged or stored, and the expression is not preserved when you leave the page. The evaluator is a hand-written parser rather than JavaScript's eval, so nothing you type is executed as code.
Frequently Asked Questions
Why does sin(30) give −0.988?
Because the calculator is in radian mode and you meant degrees. Press Deg/Rad and try again — sin(30°) is exactly 0.5.
How do I calculate a logarithm in another base?
Use the change-of-base rule: logb(x) = ln(x) ÷ ln(b).
Why is 0.1 + 0.2 not exactly 0.3?
Neither 0.1 nor 0.2 has an exact binary representation, so tiny rounding errors appear at the 17th digit. This is inherent to floating-point arithmetic on every computer, not a bug in the calculator.
Can I use the keyboard?
Yes — digits, operators, parentheses, Enter to evaluate, Backspace to delete and Escape to clear all work.