In this graduate thesis we were examining the fluency of computing in the students of the Master's Degree. The theoretical part of the paper deals with the concept of conceptual and procedural knowledge, mental computing, the use of strategies and at the end of fluency. The study on fluency of computing students of the Master's Study was conducted among the students of the first, second, third, fourth and fifth year of the Master's Studies at the University of Zadar. The study was attended by 139 participants. The research carried out qualitatively and quantitatively was carried out in the period of May 2018 in the area of Zadar County. In the quantitative part of the survey, the respondents were divided into years of study, and in the qualitative part of the volunteers were examined one at a time. The aim was to examine the individual calculation strategies and the opinion on their own mental computing and the resolution of the mental computation test. The obtained data were quantitatively analyzed, using descriptive statistics, one-way analysis of variance (ANOVA) showed a statistically significant difference in performance on different test tasks, with a risk level of less than 1%. The Fisher LSD test examined which tasks the students had solved with with greater accuracy. We conclude that hypotheses have been verified.