This study aimed to examine the relations among property strategies, working memory, and multiplication tasks with 101 Chinese fourth-grade students. Two multiplication property strategies (associative and distributive) were compared with no strategy and demonstrated differentiated effects on students' accuracy and reaction time. Associative property strategy outperformed the distributive strategy and no strategy on the measures of accuracy and reaction time. The findings support the problem difficulty effect. The findings indicate that if a strategy does not necessarily simplify a problem, it might not help to enhance accuracy, suggesting that multiplication property strategies should be used with respect to the structural features of the problems. Among more difficult problems, visuospatial sketchpad consistently explained unique variances in problem accuracy.