This fun. I'd forgotten how much of this stuff I used to know. (ps, for Q3: if you know the formula for the Harmonic series then you can answer this one very e

This fun. I'd forgotten how much of this stuff I used to know. (ps, for Q3: if you know the formula for the Harmonic series then you can answer this one very easily. If you don't, you're probably going to be a bit stuck.)