Unlock the joy of problem-solving with Pearls for Adults’ Minds.

• 99% of a watermelon’s weight is water. The watermelon was exposed to the sun, and it turned out that 98% of its weight is now water. In what percentage did the overall weight of the watermelon change?

• You have one glass of wine and another glass of water. Take one teaspoon from the wine glass, transfer it to the water glass, then transfer one teaspoon from the water glass back to the wine glass. Where is there more foreign matter: more wine in the water glass or more water in the wine glass?

• Which weighs more: iron with a mass of 1 kg or feathers with a mass of 1 kg?
• Moving the above to the moon, what will be the answer now – who weighs more?
• What weighs more on the moon than on Earth?

Why settle for ordinary riddles when you can challenge yourself with mind-bending puzzles that spark curiosity and sharpen thinking? From clever coin tricks to famous paradoxes, this book invites mature readers (and the young at heart) into a world of logic, math, Physics, and Philosophy made fun.

Inside you will discover:
• A handpicked collection of problems that grow in difficulty, from simple to complex
• Step-by-step explanations that show more than one way to solve each challenge
• Brain-building activities that develop problem-solving skills and critical thinking
• Hours of fun that expand knowledge while keeping readers entertained

Perfect for high school and above, and anyone who loves a good riddle, this book turns learning into an adventure. Pearls for Adult Minds blends play with learning, making every puzzle an opportunity to grow.

For beginners or less advanced learners, the first book – Pearls for the Young for children and teens – offers puzzles designed for fresh, enthusiastic thinkers preparing for the next level.

Nahum Izhaky holds a Ph.D. in Physical Electronics from Tel Aviv University. Led and managed research and development departments for over 25 years at Intel, Elbit Systems, Applied Materials, and several startups (Lynx Photonic-Networks and Innoviz). He has published dozens of scientific papers, contributed chapters to professional books, and holds multiple patents. Today, he leads the physics group at Prisma Photonics.