How to use this online calculator
4calcs is a free online calculator that works like a good handheld scientific calculator: type a whole expression, press =, and the answer appears with the expression above it. There is nothing to install and no account to create, and nothing you type leaves your browser.
Order of operations
Expressions follow the standard order of operations (PEMDAS): parentheses first, then powers, then multiplication and division, then addition and subtraction, working left to right. Powers are evaluated from the right, so 2^3^2 is 2^9 = 512, and a leading minus applies after the power, so −2^2 is −4. You can leave out the × sign before a parenthesis, a function or a constant: 2π, 3(4 + 1) and 2sin(30) are all read as multiplication.
The % key divides the number in front of it by 100, so 200 × 15% gives 30. For discounts, markups and percent change, the percentage calculator walks through each step.
Degrees or radians
Trigonometry follows the DEG/RAD switch at the top of the display. In degrees, exact angles give exact answers: sin(180) is 0 rather than a tiny rounding error, and tan(90) is reported as undefined instead of a huge number. Press 2nd for the inverse functions sin⁻¹, cos⁻¹ and tan⁻¹. To convert an angle from one unit to another, use the angle converter.
Memory, Ans and history
M+ adds the current result to memory and M− subtracts it; MR recalls the stored value and MC clears it, and an M appears in the display while memory holds a number. Ans drops your last answer into a new expression, so you can chain calculations without retyping. The history panel keeps your last 20 calculations while the page is open — tap any line to reuse its result.
Keyboard shortcuts and full screen
On a computer you can type directly: digits, + − * / ^ and parentheses work as you would expect, Enter or = calculates, Backspace deletes the last entry, and Esc or Delete clears everything. The letter x also multiplies, and a comma works as a decimal point. Use the full-screen button in the corner of the display for a large, distraction-free keypad on a phone, tablet or desktop; 4calcs remembers that choice on your device until you turn it off.