Question 1

What does the % button do?

Accepted Answer

It calculates the remainder (modulo), not a percentage. For everyday percentage math, use the basic online calculator.

Question 2

What happens if I take log of zero?

Accepted Answer

The calculator shows a clear error — logarithms require a positive number.

Question 3

Does this use eval()?

Accepted Answer

No. Expressions are parsed and evaluated safely in your browser without running arbitrary code.

Question 4

Can I use keyboard input?

Accepted Answer

Yes. Numbers, operators, parentheses, Enter to calculate, and Escape to clear.

Scientific Calculator

Angle mode