Online Scientific Calculator

A basic calculator applies operations in the order you press them. A scientific calculator does two things beyond that:

• It obeys the order of operations. Typing 3 + 4 × 2^3 returns $35$, because the power is done first ($2^3 = 8$), then the multiplication ($4 \times 8 = 32$), then the addition. A basic calculator would give $56$.
• It carries the functions that show up in science and algebra: $\sqrt{\;}$, $x^y$, $\log$, $\ln$, $\sin$, $\cos$, $\tan$, factorials, $\pi$, and scientific notation through the EE or EXP key.

Most of these live above the keys and are reached with SHIFT or 2nd. That is where inverse functions hide too: $\sin^{-1}$ sits above $\sin$, and $10^x$ sits above $\log$.

This online version adds one thing a handheld cannot: it shows the intermediate lines, so you can see where an answer came from.

Square roots. Press the $\sqrt{\;}$ key before the number on most modern calculators, and close the bracket: √(625) gives $25$. For a cube root use $\sqrt[3]{\;}$, or raise to the power $\tfrac{1}{3}$: $125^{1/3} = 5$. For any other root, $\sqrt[n]{x} = x^{1/n}$.

Negatives. The (-) key and the − key are different. Write $(-3)^2 = 9$ with brackets; typing -3^2 gives $-9$, because the power binds tighter than the sign.

Fractions. Use the $a\frac{b}{c}$ or fraction key rather than decimals, so $\frac{2}{3} + \frac{3}{4}$ returns the exact $\frac{17}{12}$ instead of $1.41\overline{6}$.

Trigonometry. Check the mode indicator: DEG for angles in degrees, RAD for radians. $\sin(30^\circ) = 0.5$, but $\sin(30 \text{ rad}) \approx -0.988$.

Big and small numbers. 6.02 EE 23 means $6.02 \times 10^{23}$; typing 6.02 × 10 ^ 23 works too but is slower.

• Missing brackets around a whole numerator or denominator. 12/3+1 is $5$, not $3$. Type 12/(3+1).
• Leaving the calculator in radian mode during a geometry problem, or in degree mode during calculus. Wrong-looking trig answers are nearly always a mode problem.
• Rounding partway through. Keep full precision in the calculator memory and round only the final answer; rounding $\pi$ to $3.14$ early can shift a result in the second decimal place.
• Trusting the display over the question. A calculator returns the principal square root only: $\sqrt{25} = 5$, whereas the equation $x^2 = 25$ has two solutions, $x = \pm 5$.
• Reading E as an error. 1.2E-5 is scientific notation for $1.2 \times 10^{-5}$.