What is MC MR M+ M- in calculator?

** M+ = Add to memory (i.e. Memory Add takes the number on the display, adds it to the memory, and puts the result into memory)

** M- = Subtract from memory

** MC = Memory Clear (clear stored value); Memory Clear sets the memory to 0
MRC = Memory Re-Call (recall stored value)

** MR = Memory Recall uses the number in memory, acts as if you had keyed in that number yourself (Memory Re-Call to recall stored value)

M+ (i.e. M=M+D)
M- (i.e. M=M-D)
MRC (D=M, if pressed once; M=0, if pressed twice)

For example:
You are starting with 100, type in 100 and hit M+.
Now when you press MR, 100 will be appeared.

To add 50, when 50 is displayed on the screen, hit M+.
Now when you press MR, 150 will appear.

To subtract 60, when 60 is displayed on the screen, hit M-.
Now when you press MR, 90 will appear.