MathLabs

Problem 4

Find all positive integers nn such that {n,n+1,n+2,n+3,n+4,n+5}\{n,n+1,n+2,n+3,n+4,n+5\} can be partitioned into two disjoint sets whose products are equal.
Step 2 of 4: Find the forced odd term
In plain words

The three odd positions must distribute the only possible odd prime factors, leaving one factor-free odd number.

textAmongthethreeoddterms,onehasnofactor3textor5\\text{Among the three odd terms, one has no factor }3\\text{ or }5
Detailed analysis

There are three odd numbers. At most one is divisible by 33, and at most one by 55. Therefore one odd number has neither factor 33 nor factor 55; it also has no factor 22. With the restriction above, that number must be 11.