The fastest way to reset most calculators
Press the Clear button, usually labeled C or AC. On most basic calculators, a single press clears the display and any number you were entering. On scientific calculators, you may need to press it twice — once to clear the current entry and once more to clear any stored operations or memory.
If your calculator has an All Clear button (marked AC instead of C), press that instead. AC wipes everything at once: the display, any pending calculation, and stored values. A plain C button typically clears only what you are currently typing, leaving a calculation in progress untouched.
On a graphing calculator or a calculator app on your phone or computer, look for a button or menu option labeled Clear, Reset, or Delete. The exact location varies by model, but the principle is the same — you are telling the device to forget what it was doing and start over.
Key Takeaways
- Press C or AC to clear the display and stop the current calculation on a physical calculator.
- AC (All Clear) removes everything including stored memory, while C (Clear) may leave a calculation waiting to be finished.
- Scientific and graphing calculators sometimes require two presses of the clear button to fully reset.
- Calculator apps on phones and computers usually have a clear or reset option in the main menu or as a dedicated button.
- If you cannot find a clear button, check the calculator's manual or look for a button labeled DEL, Delete, or a menu option.
Clearing memory on calculators that store numbers
Some calculators have a memory function that lets you save a number for later use. This is separate from the display and the current calculation. Pressing C or AC will not erase a number stored in memory.
To clear memory, look for a button labeled M, MEM, or MC (Memory Clear). Press it once. The display may show a small M icon that disappears when memory is cleared, or there may be no visible change — the number is straightforward gone. If your calculator has multiple memory slots, you may need to press MC multiple times or navigate a menu to clear each one.
If you are not sure whether your calculator has memory, try pressing C or AC and then typing a new calculation. If it works normally, memory was not the issue. If something unexpected happens — if old numbers appear or the calculation behaves strangely — memory may be interfering, and you should clear it using MC.
Resetting a scientific or graphing calculator to factory settings
If clearing the display and memory does not fix the problem — if the calculator is stuck, showing strange symbols, or behaving unpredictably — you may need to perform a factory reset. This erases all stored data and returns the calculator to its original state.
On most scientific calculators, hold down the C button or the AC button for three to five seconds. Some models require you to press and hold a specific combination, such as Shift and C at the same time. Check your calculator's manual for the exact key combination, as it varies widely by brand and model.
On graphing calculators like the TI-84, a factory reset is usually found in a menu. Press the Mode button or look for a Settings or Reset option. Navigate to the reset function and confirm. This process may take a few seconds and will erase any programs or data you have entered.
On a calculator app, uninstall and reinstall the app, or look for a Settings menu within the app itself. Most app-based calculators do not store data between sessions, so closing and reopening the app is often enough to reset it.
What to do if the calculator will not respond to the clear button
If pressing C or AC does nothing, the calculator may have a dead battery or a stuck button. Remove the battery for 30 seconds and reinsert it. This forces the calculator to power down completely and often clears any error state.
If the calculator runs on solar power or has a non-removable battery, press and hold the C button for 10 seconds. Some calculators interpret a very long press as a hard reset signal.
If the button itself feels stuck or does not click normally, gently press it several times in quick succession. Dust or debris can prevent a button from registering. If it still does not work, the button may be broken and the calculator may need repair or replacement.
Clearing a calculator on your phone or computer
On an iPhone, open the Calculator app and swipe left. This clears the display and any pending calculation. Alternatively, press the C button that appears on the screen.
On an Android phone, open the Calculator app and look for a C or Clear button on the keypad. Tap it once to clear the display. Some Android calculators also have a delete or backspace button that removes only the last digit you typed.
On a Windows computer, open the Calculator app and press the C key on your keyboard or click the C button on the screen. On a Mac, open Calculator and press Command+Delete or click the Clear button.
If you are using an online calculator in a web browser, look for a Clear, Reset, or Delete button on the calculator interface. If none is visible, refresh the page — this resets the calculator to its starting state.
Understanding the difference between clear and delete
A Clear button stops everything and returns the calculator to a blank state, ready for a new calculation. A Delete or Backspace button removes only the last digit or number you typed, letting you fix a mistake without starting over.
If you typed 456 and meant to type 455, press Delete or Backspace once to remove the 6. The display shows 45. If you press Clear instead, the display goes blank and you have to start the entire calculation again.
Most calculators have both buttons. Use Delete or Backspace for small corrections. Use Clear when you want to abandon the current calculation and begin a new one.
Frequently Asked Questions
What is the difference between C and AC?
C (Clear) usually clears only the number you are currently typing, leaving any pending calculation in place. AC (All Clear) clears everything — the display, the current entry, and any operation waiting to be completed. If your calculator has only one clear button, it is usually AC.
Why does my calculator still show a number after I pressed clear?
The number may be stored in the calculator's memory, not just displayed. Press the MC (Memory Clear) button to erase it. If there is no MC button, try pressing C twice in quick succession, or hold down C for several seconds to perform a deeper reset.
Can I reset a calculator without removing the battery?
Yes. Try pressing and holding the C or AC button for 10 seconds. On some models, this triggers a reset without needing to remove the battery. If that does not work, remove the battery for 30 seconds and reinsert it.
Does resetting a calculator erase programs I have written?
Yes. A factory reset on a graphing calculator erases all stored programs and data. If you have programs you want to keep, write them down or save them to a computer before resetting. Basic calculators do not store programs, so a reset affects only the current calculation.
How do I clear just one number from a calculation?
Use the Delete or Backspace button instead of Clear. This removes only the last digit you typed. If your calculator does not have a Delete button, you may need to clear the entire entry and start that number over.