Open Middle®
Directions: Using the digits 0 to 9 at most one time each, fill in the boxes to create a circle with the smallest difference between the area estimates.
Hint
How many digits of precision does pi require for this problem?
Answer
The smallest difference between the area estimates is radius = 6 units and the area is between 98 and 123 square units
Source: Robert Kaplinsky
If a zero digit is allowed, would the solution be 120 instead of 123 to have the smallest difference between the area estimates?