Old Clarrie has three dogs. The oldest is Bob, next comes Rex and Fido is the youngest. Fido is 10 years younger than Bob, and none of the dogs are the same age. When Clarrie adds their ages together they come to 28 years. When Clarrie multiplies their ages together, he gets a number. What is the smallest that this number could be? 
Overseas Competition->Knowledge Point->Combinatorics->Number Puzzles->Number Puzzles (sign of operations)->Obtaining Maximum/Minimum Values 