Bigtone53 wrote:I am just pointing out that there is rarely a single right answer for questions like these.
Actually I think there is only one answer. The only right answer follows the rules of which the riddle was made.
When the guard would pick the number 2, your solution would be 2+7=9 and you would answer 7. The guard wants to hear the answer 3, so you don't get to enter the city. Your logic is right, but it's not the same as the logic of the guard, so the answer is wrong to the guard. Sometimes you might get lucky and get the same number the guard wants to hear, but I can light a match by striking it against the box, or I can light a match by holding a burning lighter under the match head. One method is right, the other is wrong, but the results are the same.
I can solve a mathematical problem on a test by guessing the right answer, but if I cannot show the teacher that I got it by using the right mathematical formula in the right way, I will still fail the test.
Therefore, when the guard says 10, and you answer 8 with your solution, the guard will not let you enter the city.