Full expression evaluator with functions, constants, and a handful of helpful buttons. Runs entirely in your browser.
Scientific calculators are tools with conventions you need to know
Order of operations is where most scientific calculator errors originate. PEMDAS (Parentheses, Exponents, Multiplication/Division, Addition/Subtraction) is not a suggestion — it is the hardline rule that determines whether 2 + 3 * 4 equals 14 or 20. The answer is 14. If you want 20, you write (2 + 3) * 4. Parentheses are the clearest way to communicate intent to both calculators and human readers. When in doubt, add more parentheses — they never hurt.
Trigonometric functions produce wildly different results depending on whether you are working in degrees or radians, and forgetting to switch modes is the single most common source of wrong answers. Sin(90) in degrees is 1. Sin(90) in radians is 0.894. Physics and engineering mathematics natively use radians. Navigation and most everyday geometry use degrees. Know which mode your calculation requires before you start, not after you get a suspicious result.
Frequently asked questions
What is the difference between sin, cos, and tan?
All three are ratios of sides in a right triangle. <strong>Sine</strong> is opposite over hypotenuse. <strong>Cosine</strong> is adjacent over hypotenuse. <strong>Tangent</strong> is opposite over adjacent. In the unit circle, sin gives the y-coordinate and cos gives the x-coordinate of a point at a given angle. Tangent is sin divided by cos. These relationships connect circular motion, wave physics, and engineering geometry — they are not isolated formulas but expressions of the same underlying ratio.
When do I use log versus ln?
<strong>Log (log base 10)</strong> is useful for measuring scales that span many orders of magnitude — decibels, the Richter scale, pH. <strong>Ln (natural log, base e)</strong> appears wherever growth, decay, or continuous compounding is involved: compound interest, radioactive decay, population modeling. If your formula came from a physics or calculus textbook, it almost certainly uses ln. If it came from a chemistry or acoustics context, it is probably log base 10. Always check the source.
How do I enter very large or very small numbers?
Use scientific notation: <code>6.022e23</code> means 6.022 times 10 to the 23rd power. For small numbers, <code>1.6e-19</code> means 0.00000000000000000016. Most scientific calculators accept this <strong>e notation</strong> directly. Avoid typing out long strings of zeros — each zero is an opportunity for a counting error. When results display in scientific notation automatically, it means the number is outside the calculator's comfortable display range, not that something went wrong.
What does 'undefined' or 'error' mean in a scientific calculator?
Common causes: <strong>dividing by zero</strong> (undefined in standard mathematics), <strong>taking the square root of a negative number</strong> (undefined in real numbers; requires complex math), and <strong>log of zero or a negative number</strong> (also undefined). Tan(90 degrees) is technically undefined because it approaches infinity. If you get an error mid-calculation, check for these conditions in your input. Parentheses mistakes that create unintended division by zero are especially common in multi-step expressions.