How the SHIFT and ALPHA layers work
A physical scientific calculator has far more functions than it has keys, and it solves that with layers. Look above any key on the pad and you will see a small yellow caption, and on one key a green one as well. Those are the same key's other jobs.
Press SHIFT and the indicator lights in the strip above the keypad. The next key you press runs its yellow function instead of its printed one, then the layer switches itself off. So SHIFT then sin gives you sin-1, and SHIFT then log gives you 10x. ALPHA works identically for the green captions. Pressing either key twice turns it off again if you change your mind.
Why bother, when a web page has room for every key? Because most people arrive here already knowing a physical calculator, and an exam will hand them one. Keeping the same layer habit means the practice transfers. If you would rather see everything at once, the two reference cards under the keypad list every layered function.
Why 2 + 3 × 4 is 14 and not 20
This is the real dividing line between a scientific calculator and the four-function kind, and it has nothing to do with the number of keys. A basic calculator acts the instant you press an operator: type 2 + 3 × 4 and it adds first, because that is what you asked for first, and returns 20. A scientific calculator holds the whole line, reads it as a piece of mathematics, and only then answers — giving 14, because multiplication outranks addition regardless of typing order.
The ranking is the one you learned as PEMDAS or BODMAS depending on where you went to school:
- Brackets first, innermost outward.
- Then powers and roots.
- Then multiplication and division, as equals, left to right.
- Then addition and subtraction, also left to right.
That third line is where people slip. Multiplication does not outrank division; they share a rank. So 8 ÷ 2 × 4 is 16, not 1 — the division wins only because it comes first in the line. Brackets are the one way to override any of this, and they cost two keystrokes.
Missing multiplication signs are filled in the way a textbook would. 2 then π reads as 2 × π, and 3 then ( reads as 3 × (. Convenient, and worth knowing, because a stray digit beside a bracket quietly becomes a multiplication rather than an error.
Editing the line instead of starting again
The blinking bar on the display is a cursor, and the two arrow keys walk it back and forth through what you have typed. Whatever you press next is inserted at that point, and DEL removes the entry immediately to its left.
This matters more than it sounds. On a calculator with no cursor, one wrong digit forty characters into a line means retyping the line. Here it costs two arrow presses, a DEL and a digit. AC is still there for when you genuinely want to start over, and it leaves memory, Ans and history untouched.
Degrees or radians, and why it matters
An angle is a rotation, and a rotation can be counted in more than one unit. A full turn is 360 degrees, or 2π radians — roughly 6.283. The number 30 therefore describes completely different rotations depending on the unit: a modest thirty-degree wedge, or thirty radians, which is nearly five full revolutions.
The indicator in the status strip is not a preference, then. It changes the answer:
sin 30in DEG is exactly0.5.sin 30in RAD is-0.988031624093.
Neither is wrong; they answer different questions. Degrees are what geometry, surveying and most school trigonometry use. Radians are what calculus, physics and anything involving angular velocity assume. When a trig answer lands somewhere you did not expect, check this indicator before you check your method — it is the most common reason correct working produces a wrong number.
The inverse functions follow the same setting in reverse: SHIFT sin of 0.5 returns 30 in DEG and about 0.5236 in RAD, which is π/6 as a decimal.
Powers, roots and scientific notation
Powers come in three shapes here, and the difference is where the number sits relative to the key.
- x2, and x3 on its yellow layer, go after the number like a suffix. Press
7thenx2for 49. - x□ sits between two numbers. Press
2, the key, then10for 1024. - 10x and ex, on the yellow layer of log and ln, go before a number, because their base is already fixed.
Roots mirror that. √□ and its cube-root layer open a bracket in front of what follows. y√ sits between two numbers and takes the root first: 3, the key, then 8 gives 2, because 2 cubed is 8.
The ×10x key exists because scientific work is full of numbers that are mostly zeros. Avogadro's constant is 602,214,076,000,000,000,000,000; here it is 6.02214076, the key, 23. For small numbers use the (−) key on the exponent: 1.6, the key, (−), 19 gives 1.6 × 10-19, the elementary charge.
Answers switch to the same notation once they outgrow the display — beyond twelve digits before the point, or smaller than about a hundred-billionth.
Ans, PreAns, memory and history
Multi-step work always needs a figure you already have. There are four ways to get one back, and they suit different jobs.
Ans and PreAns
Ans drops your latest result into the line; PreAns, on its yellow layer, gives the one before that. Together they let you reach back two steps without writing anything down. Both are listed in the Variable panel so you can see what they currently hold.
Memory
M+ adds the current value to a running store and M− subtracts from it; MR pastes the store back and SHIFT MR clears it. It is an accumulator rather than a clipboard, which makes it right for totalling a column of figures that each need working out first. The M indicator lights whenever the store holds anything.
Letters
Six registers — A, B, C, D, x and y — hold a number under a name. Press STO then a letter to write the value on screen into it, and SHIFT STO then a letter to paste it back. Unlike memory, which is one running total, each letter is independent, so a physics problem can keep its mass in A and its velocity in x and use both in the same line. Current values are listed in the Variable panel.
History
Every completed calculation is listed on the left with its time, newest first. Tap a line and it goes back on the display so you can change one number and run it again. This is the one for checking homework, because it shows what you actually typed rather than only what it came to. The list lives in the page and clears when you leave.
Who this is for, and how it compares to a physical calculator
The keypad here follows the layout of a standard non-programmable scientific calculator — the Casio fx-991 family, the TI-30X and their equivalents — because that is what most people already have in a drawer or a school bag. Same layer keys, same broad key positions, same two-press habit for a yellow function. Practising here transfers to the device you actually sit an exam with.
It suits a few groups in particular:
- Students working through algebra, trigonometry, physics or chemistry homework, who want the answer and the working visible at once.
- Anyone revising for a test where a non-programmable calculator is allowed, who wants to build the key habits before the day.
- Engineers, lab and trades work — unit-heavy arithmetic, scientific notation, roots and logs, without hunting for the physical device.
- Teachers demonstrating a keystroke sequence on a screen the whole room can see.
One honest caveat about exams. An online calculator is for practice and homework, not for the exam room. Almost every board requires an approved physical device and bans anything with a browser. Use this to learn the keys; take the permitted calculator to the test.
Against a physical unit this has three real advantages — a cursor you can walk back into a long line, a history that keeps what you typed rather than only the answer, and nothing to run out of battery. It gives up the things a browser cannot do: it is not exam-legal, and it does not work offline.
Mistakes this calculator will not save you from
A calculator answers the question you typed, which is not always the question you meant.
- The wrong angle unit. It produces confident, plausible, wrong numbers rather than errors, which is what makes it dangerous.
- log where you wanted ln. One is base 10, the other base e. Both are valid; only one is what the question asked for.
- Rounding partway through. Copying a mid-step answer to two decimals and typing it back throws away precision the later steps then multiply. Ans, PreAns, memory and history all exist so you never have to.
- A minus sign meaning two things.
-32is negative nine, because squaring binds tighter than the sign.(-3)2is positive nine. - A layer left on. If a key does something unexpected, glance at the SHIFT and ALPHA indicators before assuming the calculator is wrong.
What this calculator does not do
Being straight about the edges is more useful than pretending there are none.
- It works to roughly twelve significant digits, the practical limit of standard double-precision arithmetic. For very long integers use the big number calculator.
- It evaluates; it does not solve. No algebra, no unknowns, no symbolic simplification — you get a decimal, not π/6.
- There is no fraction display, no matrix mode, no complex numbers and no calculus yet. Those keys are on the pad but dimmed, and pressing one tells you which stage it arrives in rather than doing nothing.
- It does not graph.
- Factorials are exact for whole numbers to 170 and use the gamma function for decimals. Beyond 170 the true value exceeds what the number format holds, so you get an error rather than a wrong figure.
- Nothing is saved between visits.
For a single operation with its method spelled out, the dedicated pages are often better: exponents, roots, logarithms, scientific notation and the quadratic formula. Other bases are handled by the binary and hex calculators.
Frequently asked questions
What do the SHIFT and ALPHA keys do?
They are layer keys, exactly as on a physical scientific calculator. Every key carries a small yellow label above it and some carry a green one too. Press SHIFT and the next key you touch runs its yellow function, so SHIFT then sin gives sin inverse. Press ALPHA and the next key runs its green function. Both cancel after a single press, and pressing the same layer key again turns it off.
Why does this calculator give 14 for 2 + 3 x 4?
Because multiplication is resolved before addition. The calculator reads the whole expression before answering, so 3 x 4 is settled first and 2 is added to the 12. A basic four-function calculator answers each key press in turn and returns 20 instead. If you want the addition first, wrap it in brackets.
How do I edit a number in the middle of a long expression?
Use the left and right arrow keys to walk the cursor through what you have typed, then type or delete at that point. DEL removes the entry immediately to the left of the cursor rather than clearing the line, so a single mistyped digit in a long calculation costs one keystroke to fix instead of starting again.
What is the difference between DEG and RAD mode?
They are two units for the same angle. A full turn is 360 degrees or 2 pi radians, so the number 30 means a thirty-degree angle in DEG and a much larger angle in RAD. sin 30 returns 0.5 in DEG and -0.988031624093 in RAD. The current mode is shown in the status strip above the keypad, and it is the first thing to check whenever a trig answer looks wrong.
What is PreAns?
Ans holds your most recent result and PreAns holds the one before it, so you can reach back two steps without writing anything down. Both are listed in the Variable panel beside the keypad, and PreAns sits on the yellow layer of the Ans key.
Can I use my keyboard instead of the on-screen keys?
Yes. Digits, a decimal point, plus, minus, asterisk, slash, caret and brackets type straight in. Enter evaluates, Backspace deletes at the cursor, Escape clears the line, the arrow keys move the cursor, and Shift toggles the yellow layer. The full list is in the keyboard reference under the calculator.
Is this the same as a Casio fx-991 or a TI-30X?
It is not an emulator of any particular model and it is not made by, or connected to, any calculator manufacturer. What it shares is the layout convention those machines use: a yellow SHIFT layer, a green ALPHA layer, and keys in broadly the familiar places. That is enough for the keystroke habits to carry over, which is the practical reason to use it for revision.
Can I use this in an exam?
No, and no browser-based calculator is. Exam boards require an approved non-programmable physical device and prohibit anything with internet access. Use this for homework and for practising the key sequences, then take your permitted calculator into the exam room.
This calculator is provided for education and general reference. Results are computed in standard double-precision floating point and are accurate to roughly twelve significant digits, which is ample for schoolwork and most professional use but is not a substitute for an arbitrary-precision or symbolic system where exactness is required. Always check the angle unit before relying on a trigonometric result. The keypad follows the layered-key convention common to scientific calculators generally; CalculatorBoss is an independent tool and is not affiliated with, endorsed by or sponsored by Casio, Texas Instruments, Hewlett-Packard or any other calculator manufacturer, and no proprietary firmware from any such device is used. Learn more about how we build and check these tools, or read our privacy policy.