Question: Queens can move horizontally, vertically and diagonally any number of spaces as illustrated. One piece 'attacks' another if it moves to the same tile that the other piece is on. How can you arrange eight queens on the board so they cannot attack each other?
Hint: Four must go on black and four on white.
Answer: Here are the two solutions. This is usually solved with guess and check although using logic may be faster. We know that each queen must be in it's own row vertically and horizontally. We also know that 4 of the queens must be on white and 4 on black. This is true because with 4 queens on the same color all of the rest of that color is venerable to attack. (It could be done with math).
Question: A rich man suddenly dies from a cut on his finger. The next day, two men appeared and claimed to be his long-lost son. They both fit the description in the will and had all the necessary documents. The family attorney proposed a blood test. One man agreed while the other point blank refused. The one who agreed was arrested for fraud at once. The second man was accepted as the heir. Why?
Answer: He was a hemophiliac, like his father, who died from a small cut. The blood test would kill him.