What happens if you dig a hole straight down into the ground? Well, Earth is a 7,916-mile-wide ball, so if you want to dig to the center of it, it’s 3,958 miles. But if you want to dig all the way through and pop out the other side, it’s the whole 7,916 miles. Either way, the center is a 10,000-degree F blob of metal, so that’s not a great way to find what’s on the opposite side.
Lace up: If you dig 7 miles down, then dig 1 more mile to beat the record, how far do you dig?
Jog: Which is cooler, 1 thousand degrees or 10 thousand degrees?
Sprint: Earth is 7,916 miles across. Close your eyes and see if you can remember that number!
Hurdle: Who digs farther, you if you dig down 6 miles a day for 6 days, or your friend who digs 5 miles a day for a whole week?
High Jump: If you dig exactly 20 miles every day, by how much will you overshoot the exact middle spot at 3,958?
Pole Vault: If you dig 10 miles the first day, 10 miles again the 2nd day, then 20 the 3rd day, then 30, then 50… how many miles do you think you dig the day after that?
Answers:
Lace up: 8 miles.
Jog: 1 thousand degrees.
Sprint: 7,916…7,916…see how long you can remember that.
Hurdle: You dig farther, at 36 miles vs. your friend’s 35. By the way that happens with any number multiplied by itself (squared): the answer will be 1 more than multiplying that number plus 1 by that number minus 1. Try it!
High Jump: Just 2 miles, since 3,960 will be a multiple of 20.
Pole Vault: 80 miles. If you noticed the pattern, each day you dig as far as the previous two days added together. It’s the famous Fibonacci series multiplied by 10, where the Fibonacci numbers are 1, 1, 2, 3, 5, 8, 13…
