The math is interesting – I wish I had been taught some of these approaches in middle and high school. It’s tough for me to follow, but very interesting. I checked the book out for my son, but now he’s going to have to wait his turn.

]]>(Hint for anyone wondering about how to get 16: look for a property the given numbers all have in common; now think of ways to geometrically visualise all numbers having this property, and see how the sequence so far pans out in these visualisations.)

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