The word <em>wishing </em>is used as a participle in this case. Although gerunds and participles look the same, they are used in different senses - gerunds generally denote nouns, whereas participles have more of an adverbial meaning.
Answer: This is confusing but I do not agree that much because,
If we simply add the highest number twice from the digits 1-9, 9+9, which is 18. So 18 is the highest number which can be reached so 20 is not a possible number. However, if the problem has said that, we can obtain all the numbers from eleven to twenty by multiplying them, then I think it is possible...
