Bill and Bob entered the expression "3 + 2 * 4" into their calculators. Bill got "20" for the answer, while Bob got "11".

The instructor concluded that Bob had a scientific calculator, but that Bill had a simpler model. How did the instructor know this? (Hint: What did Bob's calculator do differently from Bill's?)

I've punched this into my son's calculator and into the calculator that's on my cell phone, and they do give the two different answers. But the displays look a lot alike, and I'm pushing the same buttons in the same order. What am I missing?

Thank you!