Free Scientific Calculator
A free scientific calculator is the online tool for any problem a basic calculator cannot handle: powers, roots, logarithms, trigonometry, and factorials, all evaluated with the order of operations. The expression 2 + 3 × 4 equals 14, not 20, because multiplication comes before addition, and a scientific calculator knows that rule. Use the scientific calculator above for free, with no download and no sign-up, and read on to learn the order of operations that makes it work.
PEMDAS is the rule behind every result on this page: Parentheses, Exponents, Multiplication and Division, Addition and Subtraction. It is the reason 2 + 3 × 4 is 14 while (2 + 3) × 4 is 20, and the reason a scientific calculator and a cheap pocket calculator can give different answers to the same keystrokes. This page works through the classic PEMDAS examples, shows the function keys, and explains the angle mode that causes most trigonometry errors.
Enter an expression above, or tap the keys. Examples: sin(30), 2^10, sqrt(144), 5!, log(1000), ln(e).
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How a Scientific Calculator Works: PEMDAS and Functions
A scientific calculator differs from a basic one in one decisive way: it follows the order of operations, known as PEMDAS — Parentheses, Exponents, Multiplication and Division (left to right), Addition and Subtraction (left to right). This is the rule that makes 2 + 3 × 4 equal 14, not 20, because the multiplication happens before the addition. Parentheses override the order: (2 + 3) × 4 = 20, because the bracketed addition happens first. Every expression on this page is evaluated with PEMDAS, so what you type is what mathematics means, not what a pocket calculator would do if it simply worked left to right.
Beyond arithmetic, a scientific calculator provides powers, roots, logarithms, trigonometry, and factorials. The expression 2^10 = 1024, sin(30°) = 0.5, log10(1000) = 3, and 5! = 120 are all one-line jobs. Angles need care: trigonometric functions depend on whether the calculator is in degree mode or radian mode, and sin(30°) = 0.5 only in degrees, while in radians sin(30) ≈ −0.99. The calculator above shows its mode clearly, and you can switch it before evaluating any angle.
The National Institute of Standards and Technology maintains the reference values for the mathematical constants and functions these calculators implement, from pi to the natural logarithm. When a result looks surprising, the first things to check are the mode, the parentheses, and the order of operations — those three explain nearly every “wrong answer” a scientific calculator ever gives.
Step 1 — Type the Expression as You Would Write It
Enter the whole expression, including parentheses, in the display: 2+3*4, or (2+3)*4 when you mean the addition first. The calculator reads the expression as written, so the parentheses you include are the parentheses it obeys.
Step 2 — Check the Angle Mode
Before any sine, cosine, or tangent, confirm DEG or RAD. School and most practical problems use degrees; calculus and physics formulas usually use radians. A wrong mode is the single most common cause of a wrong trigonometry answer.
Step 3 — Evaluate, Then Check the Answer
Press equals and read the result, then sanity-check it: 2 + 3 × 4 must be 14, sin(30°) must be 0.5, and log10(1000) must be 3. If a familiar value comes out wrong, the mode or a missing parenthesis is the culprit, not the calculator.
Worked Examples: PEMDAS in Action
Each row shows an expression, the order in which it is evaluated, and the result. The first two rows are the classic pair that shows why parentheses matter.
| Expression | Evaluation order | Result |
|---|---|---|
| 2 + 3 × 4 | 3 × 4 = 12, then 2 + 12 | 14 |
| (2 + 3) × 4 | (2 + 3) = 5, then 5 × 4 | 20 |
| 2^10 | 2 multiplied by itself 10 times | 1,024 |
| sin(30°) | Sine of 30 degrees | 0.5 |
| log10(1000) | 10 to what power is 1,000 | 3 |
| 5! | 5 × 4 × 3 × 2 × 1 | 120 |
The first row is the example to memorise: without parentheses, multiplication happens before addition, so 2 + 3 × 4 is 14. The second row shows the override: parentheses force the addition first, so the answer is 20. The same rule explains why 10 − 2 × 3 = 4 and why 2 × 3 + 4 × 5 = 26. Try each expression in the calculator above and confirm the result, then change the parentheses and watch the answer change.
How to Use the Scientific Calculator
Type an expression or click the buttons, press equals, and the result appears with a running history of your calculations. It handles parentheses, powers, roots, logs, trigonometry, and factorials, and it remembers your last answers so you can reuse them.
- Type or click the expression. Use the keyboard or the on-screen keys; both feed the same display, and the history below records each calculation.
- Use parentheses for grouping. Anything inside parentheses is evaluated first, so (2+3)*4 gives 20 while 2+3*4 gives 14, exactly as PEMDAS requires.
- Switch DEG and RAD for angles. Tap the mode button before trigonometry: sin(30) is 0.5 in degrees and about −0.99 in radians.
- Use the function keys. The buttons for powers, square roots, logarithms, and factorials insert the function at the cursor, so 5! evaluates to 120 and log(1000) to 3.
- Reuse answers from history. Click a line in the history to load that expression back into the display and edit it, instead of retyping the whole thing.
The Function Keys, Explained
A scientific calculator’s extra keys each do one job. This table is the reference for the keys you will use most.
| Key | What it does | Example |
|---|---|---|
| x^y | Raises x to the power y | 2^10 = 1,024 |
| √ | Square root | √144 = 12 |
| sin, cos, tan | Trigonometric functions | sin(30°) = 0.5 |
| log | Logarithm base 10 | log(1000) = 3 |
| ln | Natural logarithm, base e | ln(e) = 1 |
| x! | Factorial | 5! = 120 |
| π | Pi, 3.14159 | π × 2² = 12.57 |
Common Mistakes With Scientific Calculators
Most scientific calculator errors are not arithmetic errors: they are order, mode, and parenthesis errors. Check these first.
- Ignoring PEMDAS. Typing 2+3*4 and expecting 20 is the classic error: multiplication comes before addition, so the answer is 14. Use parentheses when you mean the addition first.
- Wrong angle mode. Degrees and radians give different answers for the same angle number. Always check the mode before trigonometry, and after switching.
- Unbalanced parentheses. A missing closing parenthesis makes the whole expression mean something else, or nothing at all. Count the opening and closing brackets before pressing equals.
- Forgetting that log means base 10. On most calculators, log is base 10 and ln is base e. log(100) = 2, while ln(100) ≈ 4.61, and mixing them up is a frequent exam error.
- Trusting a rounded intermediate. Copying a rounded result such as 0.58 into the next step, instead of using the full stored value, adds error at every step. Keep full precision until the end.
Where You Will Use a Scientific Calculator
Any problem with powers, roots, angles, or logarithms needs a scientific calculator, and those problems appear in school, work, and home projects alike.
- School maths and science. Algebra, geometry, trigonometry, and physics homework all rely on powers, roots, and trig functions that a basic calculator cannot do.
- Engineering and trades. Electricians, builders, and engineers compute angles, loads, and conversions that need sines, cosines, and exponents.
- Finance. Compound interest, loan growth, and investment returns are exponential, and a scientific calculator handles the powers directly.
- Navigation and surveying. Bearings, distances, and triangle solutions are trigonometry problems, solved with sine and cosine.
- Everyday problem solving. Splitting a bill with a tip and tax, scaling a recipe by a fractional factor, or checking a square corner with Pythagoras all benefit from one careful evaluation.
Degrees or Radians: Check Before You Calculate
Trigonometric functions depend on the angle mode, and a wrong mode is the most common cause of a wrong trigonometry answer. In degree mode, sin(30°) = 0.5, cos(60°) = 0.5, and tan(45°) = 1. In radian mode, the same keystrokes evaluate sin(30), cos(60), and tan(45) with the angles in radians, giving about −0.99, −0.95, and 1.62, which are correct answers to different questions. School problems use degrees unless stated otherwise, while calculus and physics formulas usually use radians, so check the mode every time you start a trigonometry problem.
Tips for Accurate Results
Good calculator habits are mostly about checking, not typing. These five keep your answers honest.
- Work out the rough answer first. A quick mental estimate tells you whether the calculator’s result is in the right range before you trust it.
- Parenthesise generously. Extra parentheses never change a correct expression, and they prevent the most common order-of-operations mistakes.
- Confirm the mode every session. The mode can persist from an earlier problem, so check DEG or RAD before your first trigonometry calculation, not after.
- Use the history. The history line shows exactly what was evaluated, so a wrong answer can be traced to the exact expression that produced it.
- Keep full precision mid-problem. Round only the final answer; intermediate rounding is the quietest way to lose marks and money.
Scientific Calculator Quick Answers
These are the expressions people evaluate most often, each one verified against the calculator above.
| Expression | Result |
|---|---|
| 2 + 3 × 4 | 14 |
| (2 + 3) × 4 | 20 |
| 2^10 | 1,024 |
| sin(30°) | 0.5 |
| log10(1000) | 3 |
Related tools on this site: the main scientific calculator, basic calculator, square root calculator, percentage calculator, and the scientific calculator again whenever you need a fresh check.
Frequently Asked Questions
Is this scientific calculator really free?
Yes. The calculator above is free to use, with no download, no sign-up, and no limit on calculations. It runs in your browser, evaluates expressions with PEMDAS, and keeps a history of your recent calculations.
What is PEMDAS?
PEMDAS is the order of operations: Parentheses, Exponents, Multiplication and Division from left to right, and Addition and Subtraction from left to right. It makes 2 + 3 × 4 equal 14, because the multiplication happens before the addition.
Why does 2 + 3 × 4 equal 14 and not 20?
Because multiplication comes before addition in the order of operations. The calculator evaluates 3 × 4 = 12 first, then 2 + 12 = 14. To get 20, you must write (2 + 3) × 4, with parentheses forcing the addition first.
What is sin(30)?
In degree mode, sin(30°) = 0.5. In radian mode, sin(30) is about −0.99, because 30 radians is a different angle from 30 degrees. Always check the DEG or RAD mode before a trigonometry calculation.
Do I need to download anything?
No. The calculator runs entirely in your browser. Type an expression or click the buttons, press equals, and the result appears with a history of your calculations below.
Disclaimer: This calculator is for general information only. It evaluates expressions as entered; always check the angle mode, parentheses, and order of operations before relying on a result for school, work, or financial decisions.