Contrary to other languages, MUMPS reads a mathematical sequence from left to right and disregards order of operations.
SET x=2+6/2 WRITE x
x=4 (not 5)
This may take a little getting used to for some; however, parentheses take precedence in a sequence. You can use them to override the left to right precedence.
To use the previous example:
SET x=2+(6/2) WRITE x