
Calculators use a variety of symbols to represent the mathematical operations. For example, some calculators have the symbol (±) rather than (−) to enter a negative number.
Calculators also vary on how they interpret "order of operations." There are three basic types:

PEMDAS: Use the conventional order of operations that is accepted in math.

Operation Activated: Each operation activates the equal key.

RPN: Reverse Polish Notation is used by some technical calculators.


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Using the standard order of operations, you need to add the numbers in parentheses before dividing. So, (d) is a correct way to find the average.
Try confirming this by estimating the answer and then trying both ways with your calculator. The average of 50, 62, and 73 is about 60. Some calculators give $136.33 for (c) while all calculators give $61.67 for (d). The keystrokes for (d) are closest to the estimate, so (d) is a correct way to find the average.

Comments (3)
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When posting a comment, you agree to our Terms of Use.Showing 3 commentsRon Larson (author)8 years ago Thanks. I like this too. One of the great things about having the book online is that we have space to include more information, such as different key stroke sequences.0 0Guest 8 years ago I really like including the key strokes for the Calculator. I've been doing this when I lecture and students have responded positively. I capture my lecture videos with Camtasia and One Note, along with a TI Calculator on the desktop that saves key strokes. I then copy and past the key strokes into the notes so the students can view them after they are posted on Blackboard with the lecture video.0 0Ron Larson (author)9 years ago Notice that PEMDAS represents the standard order of operations, as in "Please Excuse My Dear Aunt Sally."0 0