Puzzles
Seven digits
"I'm thinking of a number. I've squared it. I've squared the square. And I've multiplied the second square by the original number. So I now have a number of seven digits whose final digit is a 7," said Dr. Dingo to his daughter.
Can you work out Dr. Dingo's number?
If you enjoyed this puzzle, check out Sunday Afternoon Maths XVIII,
puzzles about numbers, or a random puzzle.
puzzles about numbers, or a random puzzle.