Objective To determine the understanding of decimal numbers by medical laboratory scientists, doctors and nurses.

Methods A Decimal Comparison Test determined the comprehension of decimals numbers. Additional questions sought the participants’ understanding of concentrations and reference ranges, and their preferences for the presentation of clinical pathology results.

Results Of the 108 participants, 40% exhibited poor comprehension of decimal numbers. One-third of the medical laboratory scientists, a quarter of doctors, and half the nurses were characterised as lacking numeracy skills. The majority of participants (60%) thought it would be safer for results to be presented as whole numbers rather than as decimals with leading zeros.

Conclusions The number of laboratory and clinical staff who show numeracy issues that could lead to misinterpretation of clinical pathology results and contribute to medical error strongly supports recommendations that pathology results should be presented as whole numbers.