Numeracy in the workplace is much more complex than the simple application of mathematical knowledge and skills learned in school or vocational education. Although the knowledge and skills developed in compulsory education or in formal adult and vocational education and training courses play a foundational role, they are inevitably transformed within workplace or other contexts. This is in order to address ever-evolving problems that may require timely and creative solutions, not necessarily the neat mathematical solutions typically found in school texts. It is also frequently the case that when mapped onto school mathematics curricula the actual levels appear to be relatively low at first, but these need to be understood as situated within often pressured situations in relation to time, money and safety, and almost always involve dealing with other people in the process. The author of this article, under the auspices of two research grants, visited several workplaces in order to learn more about numeracy practices on-the-job in Australia. In the first section of this article the author briefly outlines activity theory, which informed the methodology and analysis for both projects. The author then reviews a selection of key findings from the international literature on mathematics/numeracy in the workplace. The third section presents findings from each project, covering a total of 21 workplace visits. This is followed by a discussion of the findings, implications for policy and practice, and a brief conclusion.