The Skin of Our Teeth
Chess Board: These are equivalent problems. Each block covers one white and one black square, but since there are an unequal number of white and black squares to be covered, the task is impossible. Similarly, every even move will take the ant to a white square. To visit all 25 squares, it has to make 24 moves, the last move taking it to a white square. With one more black than white square on the board, this is also impossible.
Chain Reaction: $3. Cut the three links of one chain and use them to join the three other chains into one 12-link chain.
Hole in the Sphere: If the hole’s diameter is zero, the problem reduces to finding the volume of a 2-inch diameter (1-inch radius) sphere, which is 4/3 x pi x 1^3 = 4(pi)/3, about 4.2 cubic inches. It’s a fun exercise to prove that this works with any 2-inch long hole in a sphere.
Largest Number: 9^99. 9^9 = 387,420,489, which to the ninth power is a 77 digit number. But 9 to the 387,420,489th power has about 300 million digits, a number 30 miles long, at the size of this text.
Water and Wine: The amount of wine in the water glass must equal the amount of water in the wine glass, since each is replacing the other. (The numbers are red herrings.)
Tennis Tourney: 124. Each match eliminates one player. After 124 players have lost, one player remains unbeaten.
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Recent field notes
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Today
Lanphere Dunes Restoration
STAFF PICK / outdoors / 9:30 a.m.-12:30 p.m. Meet at Pacific Union School. Help remove non-native invasives at the Lanphere Dunes Unit of the Humboldt Bay National Wildlife Refuge. Tools and gloves provided, wear work clothes and bring water. Carpool to the protected site. 444-1397.
44th Annual Kinetic Grand Championship Race
STAFF PICK / events, art, outdoors, sports, for kids, free / 9 a.m.-6 p.m. A 3-day, 42-mile kinetic sculpture race over land, sand, mud and water! LeMans start at the Noon Whistle on the Arcata Plaza. Follow the race through Manila, Eureka and into Ferndale on Memorial Day for the Glorious Finish. kineticgrandchampionship.com. 889-3024.
Open Gardens
outdoors / 10 a.m.-2 p.m. Humboldt Botanical Gardens, College of the Redwoods, Eureka. Roam the 44-acre fully fenced property. $5. www.hbgf.org. 442-5139.
Organic Gardening Seminar
garden / 11 a.m.-1 p.m. Shafer's Ace Hardware and Garden Center, 2760 E St., Eureka. Free lecture by Duncan McNeill on how to create a healthy environment and healthy soils for your plant’s roots. E-mail shafers@sbcglobal.net. 442-5734.
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