Problems

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Found: 25

Assume you have a chance to play the following game. You need to put numbers in all cells of a \(10\times10\) table so that the sum of numbers in each column is positive and the sum of numbers in each row is negative. Once you put your numbers you cannot change them. You need to pay £1 if you want to play the game and the prize for completing the task is £100. Is it possible to win?

Once again consider the game from Example 2.

(a) Will you change your answer if the field is a rectangle?

(b) The rules are changed. Now you win if the sum of numbers in each row is greater than 100 and the sum of the numbers in each column is less than 100. Is it possible to win?

Two clowns A and B are playing the following game. They have 33 tomatoes on a plate. One of the tomatoes is rotten and both clowns know which one. Each move they can choose one, two, or three of the remaining tomatoes from the plate and smash them into their own faces. They take turns and the clown who chooses the rotten tomato looses the game. They cannot skip the moves. Clown A starts the game. Does A or B have a winning strategy? (A winning strategy is a strategy following which you win no matter how your opponent plays.)

Becky and Rishika play the following game: There are 21 biscuits on the table. Each girl is allowed to take 1, 2 or 3 biscuits at once. The girl who cannot take any more biscuits loses. Rishika starts – show that she can always win.

Alice and Bob play a game, Alice will go first. They have a strip divided into \(2018\) identical squares. In one move, they put a \(2 \times 1\) domino block on the strip, covering two full squares. One that is not able to make their move, loses. Who has the winning strategy?

Ana and Daniel are playing a game that involves a chocolate bar. The top left square of the bar is poisoned. In each move, a player has to pick a square and take all the pieces contained in the rectangle whose top left corner is the selected square and the bottom right corner is the bottom right corner of the whole bar. The person who takes the poisoned square loses. Who will win, if Daniel starts?

Two pirates are playing a game. They have \(42\) gold coins on a table. Each of them is allowed to take either \(1\) or \(5\) coins from the table. The pirate who takes the last coin wins. Who will win – the first pirate or the second pirate?

Rekha and Misha also play with coins. They have an unlimited supply of 10p coins and a perfectly round table. In each move, one of them places a coin somewhere on that table, but not on top of any other coins already there. A person that cannot place any more coins loses. Who will win, if Rekha goes first?

Varoon and Mahmoud are given two plates of fruit. On one plate, there are \(13\) apples, on the other, there are \(16\) pears. Each of the boys can take any number of fruit from one plate when he moves. The person who takes the last fruit wins. If Mahmoud starts, who will win?

This time, Sally and Fatima have some number of books on a shelf. Every turn, each of them is allowed to take 1, 3 or 4 books from the shelf. The girl that takes the last book wins, Sally goes first. Who will win if there are: a) 14, b) 16, c) 19 books on the shelf?