Читать книгу The Ultimate Mathematical Challenge: Over 365 puzzles to test your wits and excite your mind - Литагент HarperCollins USD, F. M. L. Thompson - Страница 24
Оглавление78. The pages of a book
The pages of a book are numbered 1, 2, 3, and so on. In total, it takes 852 digits to number all the pages of the book. What is the number of the last page?
79. A letter sum
Each letter in the sum shown represents a different digit.
The letter A represents an odd digit.
What are the numbers in this sum?
80. Timi’s ears
Three inhabitants of the planet Zog met in a crater and counted each other’s ears. Imi said, ‘I can see exactly 8 ears’; Dimi said, ‘I can see exactly 7 ears’; Timi said, ‘I can see exactly 5 ears.’ None of them could see their own ears.
How many ears does Timi have?
81. Unusual noughts and crosses
In this unusual game of noughts and crosses, the first player to form a line of three Os or three Xs loses.
It is X’s turn. Where should she place her cross to make sure that she does not lose?
82. An average
The average of 16 different positive integers is 16.
What is the greatest possible value that any of these integers could have?
83. Painting a cube
Each face of a cube is painted with a different colour from a selection of six colours.
How many different-looking cubes can be made in this way?
84. A Suko puzzle
In the puzzle Suko, the numbers from 1 to 9 are to be placed in the spaces (one number in each) so that the number in each circle is equal to the sum of the numbers in the four surrounding spaces.
How many solutions are there to the Suko puzzle shown?
