"Use it or lose it" applies to your biggest muscle--your brain. These IQ-building quizzes improve your thinking power with words, numbers, and visual designs. Quick--try these five:
1. Make a six-letter word from these five: B, G, E, A, D.
2. Calculate what fraction will produce this running decimal: .166166.
3. Take one letter from each of these animals to make another animal: possum, donkey, ermine, kitten, rhesus, cayman.
4. Which number added to 100 and 164 will make them both perfect square numbers?
5. Ten people share a birthday cake.