00:00
1.
“You wrote a number on the margin here,” Martha told her husband. “Do you want to keep it?” Jack shook his head. “It’s the serial number of my new watch but now I’ve got a trick in case I forget it,” he replied. “It’s the smallest number that gives all ones when you multiply it by 13.” What was the number?
Number 8547
Number 7641
Number 9118
Previous Question
Play again
Submit
✖
Add To Leaderboard
Share your score
✖