The book has 200 numbered pages. A bookmark was placed on every seventh page and every eleventh. How many different pages were bookmarked?
Show hints
- Count the pages divisible by seven or eleven up to 200.
- Pages marked twice are multiples of 77, so count each of them only once.
Show the answer and solution
Answer: 44
Every seventh page gives 28 bookmarks, every eleventh - 18. Pages 77 and 154 are counted twice, so the answer is 28 + 18 − 2 = 44.