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MC clears calculator memory, MR recalls the value stored there, and MS stores the number currently displayed. The related M+ and M− keys add to or subtract from that stored value. Labels and behavior vary by calculator, so check your model’s manual before relying on a particular key sequence.
What the calculator memory keys mean
- MC — Memory Clear: clears the value held in memory. It is not necessarily the same as clearing the current display.
- MR — Memory Recall: brings the stored value onto the display. On the Open University’s example calculator, recalling a value leaves it in memory, so you can recall it again. The Open University explains the memory buttons.
- MS — Memory Store: saves the displayed number in memory, replacing the value already stored.
- M+ — Memory Add: adds the displayed result to the value in memory.
- M− — Memory Subtract: subtracts the displayed result from the value in memory.
Some calculators use different labels or a different arrangement of memory operations. Casio’s guides, for example, document workflows using an independent memory marked M rather than a dedicated row of MS, MR, and MC buttons.
How to store and recall a number
This example follows the Windows calculator procedure shown by the Open University:
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8 + 15 =. The display shows 23. - Press MS to store 23 in memory.
- Press C to clear the display. In this example, the stored value remains in memory.
- Enter
46 ÷, press MR, then press=. The calculator uses the recalled 23 and displays 2.
On this layout, C clears the display while MC clears memory. The meaning of C or AC depends on the calculator, so do not assume either key clears stored values.
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How to add several subtotals with M+
Memory can accumulate results when you need to total separate calculations. For example, the Open University demonstrates adding 7 × 4 and 3 × 8 to memory:
- Calculate
7 × 4 =to get 28, then press M+. - Calculate
3 × 8 =to get 24, then press M+ again. - Press MR to recall the accumulated total: 52.
The exact starting or clearing procedure can differ between calculators. The Open University notes that a calculator may work differently from its example. See its calculator memory lesson for this demonstration.
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Why C, AC, and MC may not do the same thing
A display-clear key affects what you see; a memory-clear operation affects what the calculator has stored. Those actions are distinct on some models, but labels and reset behavior are model-specific. On the Open University example, C clears the display and MC clears memory.
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Memory may also survive a display clear or even a power-off. Casio’s fx-100MS, fx-570MS, and fx-991MS user guide states: “Independent memory and variable contents are retained even if you press [AC], or turn off the calculator.” That statement applies to the models covered by that guide, not to every calculator. Read Casio’s guide to independent memory.
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Clearing all stored information can require a separate procedure. Casio’s fx-95MS/fx-500MS guide documents a model-specific process for clearing all memories; do not assume that C, AC, or MC clears every variable or memory register on other models. See that guide’s all-memory clearing instructions.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.When to check your calculator’s manual
Check the manual if your calculator lacks MS/MR/MC keys, has several memory registers, or you need to erase stored values. Look up the exact model and confirm:
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- Which keys store, recall, add to, subtract from, and clear memory.
- Whether memory survives C, AC, or turning the calculator off.
- How to clear an individual memory register versus all memories or variables.
- Whether a memory operation uses a shifted key or a menu rather than a dedicated button.
Casio’s fx-100MS/fx-570MS/fx-991MS and fx-95MS/fx-500MS documentation illustrates why the model number matters: memory operations and clearing procedures are not universal.
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