10.7. Around a circle, there are natural numbers. Between every two adjacent numbers, their least common multiple is written. Can these least common multiples form consecutive numbers (arranged in some order)?
(S. Berlov)
10.7. Around a circle, there are natural numbers. Between every two adjacent numbers, their least common multiple is written. Can these least common multiples form consecutive numbers (arranged in some order)?
(S. Berlov)
Answer: No.
Solution. Let . Denote the original numbers (in order of traversal) as ; we will assume that . Let . Suppose that the numbers are consecutive natural numbers.
Consider the highest power of two that divides at least one of the numbers . Note that none of the numbers is divisible by . Let, for definiteness, ; then and . Thus, and for some odd and . Without loss of generality, we can assume that . Then, since form consecutive numbers, among them there must be the number (since ). But this number is divisible by (since is even), which is impossible. Contradiction.
Comment. Only the answer - 0 points.
Proved that among the original numbers there are two numbers divisible by (the number is defined in the solution) - 2 points.