There are just two ways to insert four plus or minus signs between the digits 123456789 to yield a sum of 1:
1 + 23 - 45 - 67 + 89 = 1
1 - 23 + 45 + 67 - 89 = 1
Now, see if you can insert four plus or minus signs in the sequence 987654321 to make a sum of 1. There is only one solution.
Solution to the Problem:
98 - 76 - 54 + 32 + 1 = 1
James Alarie wrote:
You didn't include a zero in either the ascending nor decending string.
Putting a zero at the beginning of either string gives the same results as without it. Putting the zero at the end of either string results in no solutions.
Correctly solved by:
| 1. James Alarie | Flint, Michigan |
| 2. Riley Dolezal |
Mountain View High School, Mountain View, Wyoming |
| 3. Dalton Hereford |
Mountain View High School, Mountain View, Wyoming |
| 4. Chris Stringer |
Mountain View High School, Mountain View, Wyoming |
| 5. Auriella Haslett |
Mountain View High School, Mountain View, Wyoming |
| 6. Hannah Behunin |
Mountain View High School, Mountain View, Wyoming |
| 7. Kayle Rippetoe |
Mountain View High School, Mountain View, Wyoming |
| 8. Brooks Garris |
Lake View High School, Lake View, South Carolina |
| 9. Shay Martin |
Mountain View High School, Mountain View, Wyoming |
| 10. Kam Dellinger |
Mountain View High School, Mountain View, Wyoming |
| 11. Chad Fore | Gate City, Virginia |
| 12. Braydon Saxton |
Mountain View High School, Mountain View, Wyoming |
| 13. Nathan Atchley | Las Vegas, Nevada |
| 14. Shay Martin |
Mountain View High School, Mountain View, Wyoming |
| 15. Isaac Kampman |
Mountain View High School, Mountain View, Wyoming |
| 16. Colton Roach |
Mountain View High School, Mountain View, Wyoming |
| 17. Marley Newton |
Mountain View High School, Mountain View, Wyoming |
| 18. Ryan Woody |
Mountain View High School, Mountain View, Wyoming |
| 19. Austin Houskeeper |
Mountain View High School, Mountain View, Wyoming |
| 20. Caleb Flake |
Mountain View High School, Mountain View, Wyoming |
| 21. Cheyenne Dunn |
Mountain View High School, Mountain View, Wyoming |
| 22. Austin Smith |
Mountain View High School, Mountain View, Wyoming |
| 23. Taylor Meeks |
Mountain View High School, Mountain View, Wyoming |
| 24. Bailey Lupher |
Mountain View High School, Mountain View, Wyoming |
| 25. Keith Mealy | Cincinnati, Ohio |
| 26. Alexis Stoddard |
Mountain View High School, Mountain View, Wyoming |
| 27. Hannah Stoddard |
Mountain View High School, Mountain View, Wyoming |
| 28. Michael Reilly | Silver Spring, Maryland |