I built this class around invented problems (rather than real ones) to review percentage calculations and introduce the “1+” trick. The material parallels that in Chapter 2.

I think a large fraction of the class were willing to try to think about percentage computations in this new way. They could see (perhaps) the advantage when trying to work out the result of successive increases or decreases. A few of them have no intuition for percentages at all – getting them up to speed will be a problem.

Starting with a nominal easy-to-work-with value (often 100) really helps.

I probably should have been more careful to conclude the working backwards discussion: an increase of 12% to a value of 13,000 corresponds to an initial value of 13,000/1.12, not to 13,000*0.88.

I hope students will read this blog and comment on the class from their perspectives.

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