Question 63
For an arrangement of the digits $0$ through $9$ around a circle, a number is called a neighbor sum if it is the sum of some two adjacent digits in the arrangement. For example, the arrangement
has five neighbor sums: $4, 7, 8, 11$, and $14$. What is the minimal possible number of neighbor sums, given that each digit must be used just once?
has five neighbor sums: $4, 7, 8, 11$, and $14$. What is the minimal possible number of neighbor sums, given that each digit must be used just once?