The mathematics used by illiterate shopkeeper��

The correct answer is: should be discussed by the teachers in classrooms as an alternate strategy in solving related problems.

Step-by-Step Explanation:

1. Understanding Informal Mathematical Knowledge: Illiterate or non-formal shopkeepers often develop unique, highly efficient mental arithmetic strategies to calculate totals, make change, and manage transactions rapidly. This practical math is derived from real-world experiences and daily problem-solving context.

2. Educational Value in the Classroom: In mathematics pedagogy, connecting formal classroom concepts with students' informal, real-life experiences makes learning more meaningful and relatable. Discussing these informal methods serves as an alternate strategy for problem-solving, encouraging diverse ways of thinking and quantitative reasoning.

3. Promoting Inclusivity and Critical Thinking: Encouraging discussions around different non-standard methods helps validate out-of-school mathematical knowledge, boosts student engagement, and demonstrates that there are multiple pathways to arrive at a correct solution.