There are a number of making the rounds on Facebook of the general form:
“X percent of people got this wrong. What is the answer?
Regardless of what the correct answer is, the posts and the resultant answers illustrate two things:
1) Operator precedence rules aren’t necessarily well-understood
2) Having to work your way through a long series of operations, even simple ones, is tedious and error prone.
So what to do? The answer is simple; just use parentheses to explicitly group your operations in the order you want them to be performed. If the original question had been:
“What is the answer (5 – 5) * (5 + 5) = ?”
the comment thread would have been a lot shorter.