How Did You Know? - {day 4}

We're back with another 5-day trivia hunt!

Again, the rules: Every remaining day this week, I'll be presenting a specific challenge. Your job: come up with the answers and hold onto them! Why? Because on Monday, next week, you'll need them to solve a short puzzle. The first person to email in the correct answers and successfully show how you arrived at them (thus the title: How Did You Know?) wins a choice of any TWO t-shirts and book from our store. In addition to the above, we'll be awarding a t-shirt to one random winner who has all the correct answers. So even if you're not the first one with the right answers, there's still a chance to wind up a winner on HDYK?

And remember, we're also giving away a really big, sa-weeet prize to any winning contestant who can defend the title three months in a row. Katie Richie and Stacy Vallely are our current champions.You can read about them here.

As with previous How Did You Know? posts, comments have been turned off, but I definitely encourage you to work in teams like our present champions did. Write your friends, send around each daily challenge, conspire, work together, whatever it takes to make sure you're armed with the right answers going into next Monday's puzzle.
If you missed Day 1's challenge, you can find that right over here. Day 2 can be found this-a-way and Day 3, right here.

Today we're playing Name That Equation. On each of the following pages, you'll find different equation. Your job? Name "˜em.

Take the weekend and go over all your answers and remember to tune in Monday at 8:00pm ET (5:00pm PT) for your final challenge.