Medium
Pig Riddle
You have seven pens and nine pigs. You must arrange the pens so that each pen has an even number of pigs. Zero is not allowed, nor will it work. How do you do this?
Choose an answer
A.Combine pens in pairs
B.Use only even-numbered pens
C.Split the pigs unevenly first
D.Stack the pens.
Answer: Stack the pens.
By stacking (nesting) the pens inside one another, all nine pigs can occupy the innermost pen together, an even number counted as one grouping that satisfies the puzzle's trick.