Efficiency of time use is a key factor in chemistry calculation tasks, affecting both, personal and professional domains. This study is dedicated to finding the fastest methods for accomplishing chemistry tasks. Our investigation delves into the comparative temporal outlays made by students as they engage three different approaches: using an electronic calculator, a basic calculator app on a smartphone, and a desktop computer calculator. As part of our research, we examine a cohort of 52 Slovenian university students, preservice teachers who were actively enrolled in chemistry and related science programs, spanning the academic years of 2019 and 2022. The results from 2019 show that students can solve the chemistry tasks most quickly using electronic calculator and take the most time to calculate the tasks using smartphones (Δmean = 133 s; ΔSD = 5 s; Δmin = 97 s; Δmax = 131 s). An even larger difference is observed from the 2022 study year (Δmean = 189 s; ΔSD = 129 s; Δmin = 170 s; Δmax = 625 s). In summary, although smartphones are recognised as a multitasking device, replacing traditional single-purpose devices, they have not been able to outperform them.