Mikołaj’s riddle: Chris has his eyes covered. In front of the boy in the basket there are 7 red apples and 13 green apples. What minimum number of apples must Chris take to make sure that two of them are the same colour?

Krzysztof's riddle: Which of the actions is first: multiplication or division?

Kinga’s riddle: How many times can you subtract 5 from 25?

Amanda's riddle: The sum of three numbers is 42. The difference between the two smallest is 6, and their sum is 4/3 of the largest number. What three numbers meet these conditions?

Tymon ’s riddle: How many nines are there between 1 and 100?