Is it true that among any six natural numbers one can always choose either three mutually prime numbers or three numbers with a common divisor?
The White Hare was very good at keeping his accounts. Every month he wrote his income and expenses in a big book.
Alice looked into his book and discovered that during any five consecutive months his income was less than his expenses, but over the past year his total income was larger than his total expenses. How could it be?
(a) Is it true that among any six natural numbers one can always choose either three mutually prime numbers, or three numbers, such that each two have a common divisor?
(b) Is it true that among any six people one can always choose either three strangers, or three people who know each other pairwise?
(a) Can you represent 203 as a sum of natural numbers in such a way that both the product and the sum of those numbers are equal to 203?
(b) Which numbers you cannot represent as a sum of natural numbers in such a way that both the product and the sum of those numbers are equal to the original number?
(a) The sum of some numbers is equal to one. Can it be that the sum of the cubes of these numbers is greater than one?
(b) The sum of some numbers is equal to one. Moreover, it is known that each of the numbers is less than one. Can it be that the sum of the cubes of these numbers is greater than one?
Do there exist two such triangles that the sides of the first triangle are all less than 1 m, the sides of the second triangle are all greater than 100 m, but the the area of the first triangle is greater than the area of the second triangle?
Does there exist a polygon intersecting each of its own sides only once (each side is intersected only once by a different side) and has all together (a) 6 sides; (b) 7 sides.
Is it possible to make a hole in a wooden cube in such a way that one can drag another cube of the same size through that hole?
Is it true that for any point inside any convex quadrilateral the sum of the distances from the point to the vertices of the quadrilateral is less than the perimeter?
In how many ways can you rearrange the numbers 1, 2, ..., 100 so the neighbouring numbers differ by not more than 1?