Mathematics is a gateway to science-related careers and all stakeholders want to improve the achievement levels in mathematics. In this study we use data from the Trends in International Mathematics and Science Study 2015 to investigate the association between the learner situational factors of gender, grade level age appropriateness, school location and test language familiarity with the mathematics achievement. We are particularly interested in whether gender can predict mathematics achievement, after taking into account these learner situational factors. The study used multiple regression to investigate the association between the variables where the mathematics achievement scores were calculated out of a possible 1000 scale points, with a mean of 500. The average score for the South African participants was 372. The regression predicts that learners who attend school in a rural and small village school are expected to achieve 63 and 48 points lower, respectively, than their counterparts from a similar background. In terms of the age effect, the regression predicts overall that a learner who is above the expected age for Grade 9 will get 60 points lower than a learner who is at the appropriate age the grade from a similar background. Furthermore the results show that if school location, familiarity with the test and age appropriateness are held constant, boys do better on average than girls by seven points and this is a significant effect. This result is unexpected since in the original data, the mean of the girls' scores was on average higher than that of the boys. The study illustrates that gendered differences can only be adequately understood when other situational factors are considered. In order to improve the equity of the outcomes, targeted systemic interventions are necessary, which focus on improving the effectiveness of instruction and quality of learning opportunities so as to mediate the effect of these situational factors.