Type the whole expression, not one step at a time
This calculator evaluates a complete expression in one pass, the way you would write it on paper: (25^2 + 40^2)^0.5 returns 47.1699056603 directly, with the standard order of operations applied — parentheses first, then powers, then multiplication and division, then addition and subtraction. That is the main advantage over a button-chain calculator, where each intermediate press commits a step and a mistyped operator forces you to start over. Here you can see the whole computation, edit any part of it, and re-evaluate.
A few notational conveniences are handled for you: ^means “to the power of”, π or pi inserts the constant, and implicit multiplication like 2(3+4) is expanded to 2*(3+4) automatically. Function names always take parentheses: sqrt(144), log(1000), fact(6).
DEG vs RAD: the switch that causes most wrong answers
Every trigonometric mistake we could list comes down to one toggle. In DEG mode, sin(30) is 0.5 — the answer school problems expect. In RAD mode, the same input asks for the sine of 30 radians, which is about −0.988. Neither answer is wrong; they are answers to different questions. Degrees are the convention in school geometry, surveying, and most everyday contexts. Radians are the native unit of calculus, physics formulas, and every mainstream programming language, because they make the derivatives of sin and cos come out clean.
The inverse functions respect the same setting: in DEG mode atan(1)returns 45; in RAD mode it returns 0.785398163397, which is π/4. If you are checking a formula from code against this calculator, switch to RAD first — that single step reconciles most “the computer disagrees with my calculator” sessions.
What the calculator does about floating-point noise
All arithmetic runs in double-precision floating point, the same number format used by spreadsheets and most programming languages. It is accurate to roughly 15–16 significant digits, but it cannot represent most decimal fractions exactly — the raw result of 0.1 + 0.2 is 0.30000000000000004. To keep answers readable, this calculator rounds every result to 12 significant digits, which folds that kind of representational noise back into the number you expect: 0.1 + 0.2 displays as 0.3.
Two related behaviors are worth knowing. First, results smaller than 10⁻¹² in magnitude snap to exactly zero, so sin(180) in DEG mode shows 0 rather than a stray 1.2 × 10⁻¹⁶ left over from the approximate value of π. Second, quantities that are mathematically undefined can still evaluate to a huge finite number for the same reason: tan(90)in DEG mode returns a value around 1.6 × 10¹⁶ instead of an error, because the computed angle is a hair short of a true right angle. If you see an absurdly large trig result, read it as “undefined”, not as data.
The function set, briefly
sin, cos, tan and their inverses asin, acos, atan follow the angle mode. log is base-10 and ln is natural — log(1000) is 3, ln(E) is 1. sqrt and abs do what they say; pow(x, y) and x^y are interchangeable. fact(n) computes factorials for whole numbers from 0 to 170 — handy for permutation and combination checks like fact(6) / (3 * 2), which returns 120. Beyond 170 the true value exceeds what double precision can hold (171! is larger than 1.8 × 10³⁰⁸), so the calculator reports an overflow rather than returning a misleading Infinity.
ANS inserts the last result, which turns the calculator into a running tape: evaluate a subtotal, then build the next expression around ANS instead of retyping. The history list keeps your last eight evaluations, and clicking one reloads the full expression — not just the answer — so you can correct one number in a long formula without reconstructing it.
Frequently asked questions
Why is my trig answer different from the textbook?
Almost always the angle mode. In DEG mode sin(30) is 0.5, the textbook answer. In RAD mode the same keystrokes compute the sine of 30 radians, which is about −0.988 — a completely different number. School problems are usually in degrees; calculus and programming formulas are usually in radians. Check the DEG/RAD toggle before anything else.
What is the difference between log and ln?
Here log is base-10 logarithm and ln is the natural (base-e) logarithm, following calculator convention: log(1000) = 3 and ln(E) = 1. Be careful when moving between this tool and programming languages — in most languages the function named log is the natural logarithm.
Why does sin(180) show exactly 0 instead of a tiny number?
Computers store π only approximately, so the raw result of sin(180°) is a number around 10⁻¹⁶ rather than a true zero. The calculator snaps anything smaller than 10⁻¹² to zero so that results read the way the mathematics intends instead of leaking floating-point noise.
Why does factorial stop at 170?
Numbers here are stored in double-precision floating point, which tops out near 1.8 × 10³⁰⁸. 170! is about 7.3 × 10³⁰⁶ and still fits; 171! does not, so the calculator raises an overflow error instead of returning Infinity. Factorial also requires a non-negative whole number — fact(2.5) is rejected.
How does the % key work?
It divides the preceding value by 100, so 25% evaluates to 0.25 and 200 * 10% gives 20. It is a plain mathematical percent, not the “add tax” style percent found on some shop calculators.
How do I reuse a previous result?
Press ANS to insert the last computed value into the expression, or click any line in the Recent calculations list to reload that full expression for editing. History keeps the last eight evaluations.