Memory keys let you park a number in the background and pull it back later, while the main display stays free for the calculation in front of you. This calculator has five of them: MC, MR, MS, M+, and M-. M+ adds the current value to memory, M- subtracts it away, and a running total can accumulate across as many steps as you like.

Key Takeaways

M+ adds the current value to memory and M- subtracts it; both are for keeping a running total.

MS replaces any stored value, MR recalls it into the expression, and MC clears memory to zero.

Storing 2.5, then 3.25, then 4.75 with M+ gives a memory of 10.5 when you press MR.

The stored value lives only in your browser, survives page reloads, and shows a small M badge while it is held.

What the memory keys do

Memory is a single slot that survives from one calculation to the next. The five keys and what each one does:

MC clears memory to zero.
MR recalls the stored value and puts it back into the expression.
MS stores the current value, discarding whatever was there before.
M+ adds the current value to the stored value.
M- subtracts the current value from the stored value.

The calculator function reference lists the keys along with the rest of the keypad, and the keyboard shortcuts page shows how to reach them without the mouse.

Keeping a running total with M+

The classic use of memory is a running total. Add each item as you go and recall the sum at the end, without writing anything down.

Worked example: a three-item total. You have three amounts to add: 2.5, 3.25, and 4.75.

Type 2.5 and press M+. Memory holds 2.5.
Type 3.25 and press M+. Memory holds 5.75.
Type 4.75 and press M+. Memory holds 10.5.
Press MR and 10.5 enters the expression.

The whole sum works on one line as a sanity check: 2.5+3.25+4.75 → = 10.5.

Taking amounts back out with M-

When part of the total is no longer wanted, subtract it with M- instead of wiping memory and starting over.

Worked example: 50 minus 12 plus 8. Type 50 and press M+. Type 12 and press M-. Type 8 and press M+. Memory now holds 46. Press MR and 46 appears. The one-line check is 50-12+8 → = 46. The memory path lets you build that total one entry at a time, which is the point of the keys: assemble the answer while the numbers arrive.

MS versus M+

MS and M+ sound alike but behave differently. MS replaces whatever is stored, wiping the old value. M+ adds to what is there, which is what you want while a total is still being built. If you press MS in the middle of a running total, the earlier running total is lost. The distinction matters most at the boundary between tasks: one MS of the new value resets memory for the next job.

When memory is worth using

Memory pays off whenever an answer needs a number you mistyped earlier, or when a subtotal has to sit untouched while you recompute another part. On this calculator you could retype the value instead, but memory removes the risk of retyping it wrong. A total that mixes additions and subtractions is the most natural fit: a start of 50, a deduction of 12, and a refund of 8 lands on 46 with one M+, one M-, and one more M+, and the running total stays visible the whole way. With memory you never hold a multi-digit number in your head while reaching for the next one, which removes a whole class of transcription slips. The how-to-use-a-scientific-calculator post walks through the wider workflow, and the memory keys slot into it whenever a value has to survive while you do something else.

The stored value stays on your own device. It lives in your browser’s local storage, so it survives page reloads and is separate from the History panel, which keeps the full list of past results. A small M badge appears near the display whenever memory holds a value, so you always know when a total is in flight.

Frequently asked questions

What is the difference between M+ and MS?

M+ adds the current value to whatever is stored, building a running total. MS replaces the stored value outright, discarding the old total, which is what you want when starting a new job.

Where does the stored value live?

In your own browser. It survives page reloads and stays on your device; nothing leaves the page. The small M badge near the display shows whether memory is currently holding a value.

How do I clear memory?

Press MC. It sets memory to zero and removes the badge. If you only need to replace the value, skip MC and use MS with the new number.

Can I use the memory keys without the mouse?

Yes. The keys have shortcuts, which the keyboard shortcuts page lists, so memory works the same way whether you click or type.