Tuesday, August 28, 2018

Knights and Liars





On the island "Lie-truth" there are living knights who always tell the truth, and liars who always lie.

A traveler met three islanders and asked each of them: "How many knights are among other two islanders?".

The first one answered: "None".
The second one said: "One".

What did the third one say?



Sunday, August 19, 2018

Find the number






Find the smallest number for which you know the following:

When it divided by 2, it gives 1 in the remainder, when it divided by 3 it gives 2 in the remainder, when divided by 4 it gives the remainder 3, when divided by 5 it gives the remainder 4, and finally when dividing by 6 it gives 5 in the remainder. But on 7 this number is divided completely.


Sunday, August 12, 2018

Eggs



Today's exercise is about a woman who was carrying eggs. Be careful and try to translate exercise to algebra first.



Elizabeth was carrying a basket of eggs for sale. David met her and by carelessness pushed her such that the basket fell to the ground and all the eggs were broken. 

David wanted to pay the woman the cost of broken eggs and asked how many of eggs were there. 

"I do not remember" Elisabeth said, "I only remember that when I rearranged the eggs by 2, there was only one egg left." In the same way, there was always one egg left when I rearranged them by 3, 4, 5 and  6. When I rearranged them by 7, then there was not a single egg left." 

The question is, how many eggs were there? Please state the smallest such number.


Sunday, August 5, 2018

The Cunning Employee



Today, I want to share with you and ask to solve an old, interesting problem about how an employee cunningly deceived the store owner. Here is the problem:

The owner of the store arranged in his cellar a cabinet in the form of a square with nine compartments. The middle one he left free for empty bottles, and in the rest he arranged 60 bottles of wine so that in each corner compartment there were 6 bottles, and in each of the rest by 9 bottles. 


Thus, on each side of the square there were 21 bottles. The employee noticed that when the owner  was checking the number of bottles, he only counted the bottles on the sides of the square and made sure that on each side of the square there were 21 bottles. Then the cunning employee first time took away 4 bottles, and the rest arranged so that again the sum of the bottles turned 21 on each side. The owner counted the bottles in his usual way and thought that the bottles remained the same number and that the employee only moved them. The employee took advantage of the owner's mistake and again took away 4 bottles, placing the rest so that on each side of the square there were again 21 bottles. The same he kept repeating until it was possible. 

The question is, how many times did he take bottles and how many bottles did he take away?