ReactOS Calc reserves for the user a memory region for storing data.
With this feature, the user can store frequently used numbers (typically, these numbers are constants) and recall them at any time, without the need to re-enter them manually.
If the memory function is currently in use, the text "M" will appear in the right box underneath the base change option set.
The memory is preserved when switching between standard and scientific mode, but its content is lost when ReactOS Calc application is closed.
Four keys are available with memory function support.
Memory Clear: clears the content of the memory.
Memory Recall: retrieves the stored data from the memory and it shows it into the output display, without affecting the content of the storage.
Memory Store: stores the displayed value into the memory. The content of the display is unaffected. After pressing this button, the previous content of the memory is lost.
If the 
modifier is activated, then this button will swap current memory value with displayed
value. Under these conditions, the displayed value is stored and the previously stored quantity
is shown on the output display.
If the memory is empty, it will act as a normal store.
Memory Sum: the displayed value is algebraically added to the current memory. The output display will be unchanged after this transfer and addition.
If the
modifier is activated, then the displayed value will be algebraically subtracted from the memory. If the memory is
empty, it will work in both condition as a simple memory store.