Question 5
In $1\star2\star3\star4\star5\star6\star7\star8\star9\star10$, replace each star by + or − so that the result is 25. Find as many different replacements as possible. Example: $1-2-3-4+5-6+7+8+9+10=25$.
IMSO Maths · IMSO 2009 Mathematics - International Exploration