In chapter 24 of *How Many Licks*, Aaron Santos estimates how long of a line could you write before one pen ran out of ink?

The beginning of the school year can be a fun time. Ignoring the uneasiness that comes at the though of another exam-filled nine months, there are the fresh new supplies of pens, bags, and Trapper Keepers that you get every September. But inevitably, the pens run out, get lost, or are stolen so that by the time June rolls around, you’re left with a completely different gaggle of pens than you started with. What if you could maintain your original supply of pens? How long of a line could you write before one pen ran out?

1) 1 km (~0.6 mi)

2) 3 km (~1.8 mi)

3) 5 km (~3.1 mi)

[Helpful Hint: Factoring in losing pens and using up pens, assume that a pen lasts about two months (60 days). And assume you take about 10 pages of notes per day, with 20 lines per page, and about 0.25 mi (~10 in) of ink written per line = 50 m (~160 ft) of ink used per day]