A harvest sown and reaped on the same day
In an unplowed field,
Which increases without growing,
Remains whole though it is eaten
Within and without,
Is useless and yet
The staple of nations.
If a cork is placed into a glass of water, it will almost always drift to the side of the glass. There is one simple way, however, to get the cork to float in the center of the glass. What is it?
Water, the glass, and the cork are all that is required.
The reason that a cork drifts to the side of a glass is that it floats to the highest point. Since water “clings” to the glass, the highest point is around the edge of the water. To get the cork to float in the middle of the glass, all you have to do is fill the glass as much as possible. The water will form a convex shape above the glass, with the highest point at its center. This is where the cork will settle.
A zebra was going to the river. On the way the zebra encountered five giraffes. Each giraffe had five monkeys on their neck. How many animals were going to the river?
I’m not the sort that’s eaten, I’m not the sort you bake,
Don’t put me in an oven, I don’t taste that great,
But when applied correctly, around me you will find,
Problems are so simple when my digits come to mind.
A variation of this brain teaser includes laser printers (they were invented by Gary Starkweather) and bulletproof vests (invented by Casimir Zeglen using silk, though modern vests use Kevlar, so it’s halfway right).