fx-82MS fx-82TL
M−
On a Casio calculator you can subtract a result from memory
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M+  .gif)
When this variable contains data, it is shown in the display by an M. Answer memory contents are updated with result whenever you press the M- key.
Example 1
To subtract 3 from the value 123 that was stored in variable M
M 3 M+ 3M-
3.
and show the new value
M RCL M M=
120.