Open Middle®
Directions: Using the digits 1 to 9, at most one time each, place a digit in each box to fill in the circles of the triangle. The sum of the numbers on each side of the triangle is equal to the length of that side. Arrange the numbers so that the triangle is an equilateral triangle.
Hint
What are the criteria for an equilateral triangle?
Answer
There are many possible answers. See one possible answer below.
Source: Erick Lee
Is there a solution where the side lengths are something other than 23?
We got all sides to be 17. Starting at a corner, we did: 1, 8, 6, 2, 5, 7, 3, 4, 9.
1,6,8,4,3,5,7,9,2,1,
1,6,8,5,2,4,9,7,3,1,
I did starting at the top corner, 9,5,1,8,2,6,7,4,3.