What do Nancy Drew, Sherlock Holmes and Miss Marple have in common? These famous fictional detectives all have an uncanny ability to crack tough cases. Even if you don’t stumble across mysteries in your daily life like these gumshoes do, seeking out a brain teaser, puzzle or riddle now and then offers a fun way to keep your mind sharp.

You’ll hone some of the same mental skills detectives use to do their work. These abilities include analytical skills, an eye for detail, resourcefulness and tenacity. Keeping these attributes sharp also can pay off by helping you solve challenges you face every day — from planning a vacation to making a medical decision.

Mysteries are a type of logic puzzle in which you get hints you must use to figure out a solution. Logic puzzles come in many forms, from word stories to math problems. But all logic games can help you improve these cognitive skills:

  • Critical thinking
  • Problem-solving
  • Reasoning

Some research shows that games, puzzles and other “informal mentally stimulating activities” may even lower the risk of cognitive impairment and dementia, according to the National Institute on Aging. How do these activities help the brain? They may create “cognitive reserves” that can assist the brain in adapting to changes caused by aging or health issues.

More research is needed, but some studies show that adults 65 and up who participated in brain training that involved their memory, reasoning and processing speed all had mental gains that lasted for two years.

So try your hand at “Can You Find the Mystery Number?” — a math and logic puzzle that will let you dust off your detective skills and study clues to come up with a solution. You’ll have to analyze the relationship of the numbers in the first two triangles to solve the mystery of the missing number in the third triangle. If you get stuck, scroll down for a hint or scroll to the bottom for the answer.

What's Your Number

Are you stuck? Here’s a hint: Addition, multiplication and division are all required to find the answer. Still stuck? Scroll to the bottom for the answer.

Answer To What's Your Number

How’d you do? Did you find this brain teaser easy or challenging? Let us know in the comments and try our other brain teasers.