A grounded theory approach was employed to explore the variation in strategies used by students when solving mental multiplication problems. Metacognitive prompts, externally generated stimuli that activate thoughtful cognition, were automatically generated via computer during the solving of mental multiplication problems to elicit awareness, understanding, and reflection of problem-solving strategies. Students' responses to the prompts were analyzed and indicated students envisioned, evaluated, and tested various strategies when solving mathematics problems. Qualitative analysis was used to develop a metacognitive prompting model of problem solving consisting of conceptual, procedural, and behavioral-based strategies. Our findings suggested that the judicious use of metacognitive prompting may be a catalyst to help encourage students to use reflective cognition. Implications for instruction, limitations, and suggestions for the use of metacognitive prompting are discussed. (Contains 1 table and 7 figures.)