1] You have N coins laying flat on a table, each with a head side and a tail side. few of them are heads up, few are tails up. You can't feel, see or in any other way find out which side is up. Split the coins into two piles such that there are the same number of heads facing up in each pile. How did you do it?

2] You have two hourglasses. One empties in 7 minutes.
The other empties in 4 minutes.
How can you use these two hourglasses
to measure exactly 9 minutes?

3] The most common way to find the area of a triangle is to take half of the base times the height. Numerous other formulas exist, however, for finding the area of a triangle, depending on what information you know. Using information about the sides and angles of a triangle, it is possible to calculate the area without knowing the height.