What does the M+ key on a calculator do?

The M+ key on a calculator is designed to add the current value displayed on the screen to the calculator's memory. When you press M+, the value that is currently being shown is summed with whatever is already stored in the memory. This function enables users to accumulate a total without having to repeatedly write down intermediate results or perform additional calculations manually. As a result, using the M+ key facilitates more efficient data entry and management during calculations that involve multiple steps or values, particularly in scenarios involving long series of additions or financial calculations where precise tracking of totals is required. This functionality is crucial for ensuring that users can operate effectively in complex mathematical tasks where memory recall and addition play significant roles.