Mathematics · pattern D, Mode switcher
Pick an operation and enter a value. The result arrives with the related quantities and the domain restriction that applies, rather than an error message you have to interpret.
each operation applied to a single value x
Deliberately not a keypad. Showing one operation with its domain and its related values is more useful for learning than a grid of buttons that hides the step.
12.00000000
Square root; undefined for negative x in the reals.
Square roots of negatives, logs of zero and factorials of fractions are all undefined in the ordinary reals, and most calculators answer with a terse error. Knowing which operation carries which restriction is part of understanding the function, so this page states the domain rather than merely refusing.
If the number is not the part you are stuck on, that is what the service is for — a specialist who explains the working, not just the answer.
Arithmetic runs in double-precision floating point, so results beyond about fifteen significant figures are not exact. Where a question wants an exact fraction or surd, keep the exact form rather than a decimal.