Do you like brain teasers? These can help test your common sense and your ability to think out of the box. Brain teaser puzzles can test your critical thinking and problem-solving skills. Solving these can be fun, especially when you try them along with your friends, family or colleagues. Even if you are unable to solve a particular challenge, regularly practicing them can help boost your intelligence and improve your concentration power.If you are a fan of brain teaser challenges, here is one with an optical illusion. In...