<![CDATA[Understanding mathematical concepts is essential for high school students, as it enables them to apply mathematics in real-life contexts, including financial management. This study was conducted to examine the classical mastery and the effect of Game-Based Learning (GBL) assisted by Cashflow MathPoly integrated with financial literacy on students’ mathematical conceptual understanding at SMA Negeri 1 Grabag. A quantitative approach was applied using a quasi-experimental design with a nonequivalent control group. The participants consisted of 60 students, with class XI F-1 as the experimental group (28 students) and class XI F-2 as the control group (32 students). The research instruments included a mathematical conceptual understanding test (pretest and posttest), interview guidelines, and observation sheets. Data analysis was carried out by examining the equivalence of students’ initial abilities using an Independent Samples t-test. The findings confirmed that both classes had comparable initial abilities. The experimental class achieved a learning mastery level of 80.29%, while the control class reached only 50%. The classical mastery analysis further showed that the experimental class fulfilled the criteria of classical achievement (Zcount =1.746 > Ztable=1.645), while the control class did not achieve classical achievement (Zcount =-3.265 < Ztable=1.645). Moreover, the Independent Samples t-test result that (tcount =4.25 > ttable=2.00172), demonstrated that students who learned through the GBL model possessed higher mathematical conceptual understanding than those who were taught using direct instruction.]]>
