Previous research has drawn attention to the difficulties associated with developing a mathematical competency. Forty grade 3 pupils taking the national tests in mathematics was assessed with respect to their working memory capacity and anxiety about testing. The pupils seemed not to understand algorithms, and they reported that they were anxious about them. In the current paper, the data were revisited and further analyses conducted in order to examine whether there were any differences in working memory load and test anxiety between algorithms associated with subtraction and those for addition. The result reveal that the working memory load was heavier and the anxiety level higher for subtraction compared to addition. Solution strategy and cognitive overload, might explain this.