Simple math tells us that if the Al Franken forces and the Norm Coleman camp keep ramping up the ballot challenges, they’ll reach a combined total of 1,732 challenged ballots by the end of Minnesota’s U.S. Senate recount. That’s if each campaign continues to increase its number of challenges in the neighborhood of 140 per day, as they did from Day One to Day Two.

(Minnesota Secretary of State Mark Ritchie predicts 1,500 challenged ballots, and fivethirtyeight.com’s Nate Silver estimates roughly 1,800. But since every campaign challenger at every recount site represents an independent variable, I think my guess is as good as theirs.)

More complicated math, working with the rate of increase rather than the hard-number jump, suggests the combined total could hit 2,518. That’s if each campaign were to continue to become increasingly picky over the next two days — at the same percentage rate of increase they showed from Day One to Day Two.

For Franken, the day-over-day increase so far is 42 percent, which if repeated on Day Three and Day Four of a projected four-day recount, would lead to a total of 1,233 challenges.

For Coleman, who had a 44 percent increase from Day One to Day Two, the grand total would be 1,285 challenged ballots, if he were to keep increasing his challenged ballots by 44 percent each day. Drilling down, that means he would challenge 373 on Day Three. And on Day Four, Coleman’s daily challenged ballot count would be – hold on to your hat, Nate Silver! – 538.