The aim of this study is to explore high-school school mathematics teachers' topic-specific pedagogical content knowledge. First, 639 high-school students were asked to give explanations about "a[superscript 0] = 1, 0! = 1" and "a [division] 0" where a [not equal to] 0. Weak explanations by the students led to a detailed research on teachers. Fifty-eight high school mathematics teachers in Northern Cyprus were the participants. They were asked to write how they teach the above topics to high school students. The researcher determined some categories and themes from the written explanations of the teachers using inductive content analysis. Then, three pre-service mathematics teachers had a four-hour training on deductive content analysis. The pre-service teachers went over the written explanations independently and used the pre-determined categories and themes to code the explanations in a deductive way. The results indicate ([chi][superscript 2]) that experienced teachers propose more conceptually based instructional strategies than novice teachers. The results also indicate that strategies proposed by all the participants were mainly procedural, fostering memorization. Hence, giving teachers the opportunity to view and teach mathematics in a more constructivist way and more emphasis on topic-specific pedagogical content knowledge in teacher training programs are recommended. (Contains 3 tables and 1 figure.)