This article reports the findings of classroom research exploring the potential of posing challenging mathematical problems situated in real-world financial contexts to activate mathematical knowledge, skills and reasoning. The Organisation for Economic Cooperation and Development (OECD) Programme for International Student Assessment (PISA) 2012 mathematical literacy assessment framework (OECD, 2013) provided theoretical framing for the study, which examined the use of a "financial dilemma" titled "Shopping for shoes" in a Year 5/6 composite class in a suburban Australian primary school. The social and mathematical dimensions of the task, together with a particular lesson structure, successfully engaged 10 to 12-year-old students in exploring mathematics through a financial problem-solving experience. The findings reveal that students' notions of friendship and fairness guided the way they "formulated" the problem and "employed" mathematics. Strategies intended to encourage students to "interpret" the alignment and reasonableness of their social and mathematical thinking against the problem context were critical to the lesson.