I cost no money to use, or conscious effort to take part of. And as far as you can see, there is nothing to me. But without me, you are dead.
Answer: air
Select a pack of riddles and try to solve it in an interesting way.
This riddle appears in the following downloadable PDF files:
Einstein said that only 2% of the world could solve this problem. Can you do it?
Complete the grid by using logic and the given clues of each problem.
Use logic deductions to solve problems that are similar to the Einstein's Riddle.