You have two books. One of them is upside-down and the other is rotated so the top of the book is facing you.
What is the sum of the first page in each book?
A book has 500 pages:
The 1st page says "Exactly 1 page in this book is false." The 2nd page says "Exactly 2 pages in this book are false." ... The 500th page says "Exactly 500 pages in this book are false." Can any of the pages be true?
Two digits are selected at random from digits 1 through 9. If sum is even, find the probability that both numbers are odd?