Word problem solving combines linguistic and mathematical processes, includingreading and calculating. However, it is still unclear how strongly these processesoverlap, e.g., if calculations occur parallel or serially during reading. Also, it is unclearhow much the mental representation created during reading and the mentalrepresentation in which calculations are integrated (e.g., Thevenot et al., 2007). In thepresent study, we present data from an experiment that investigated the overlapbetween reading and calculating based on the observation of eye movements duringword problem solving.We systematically varied three-line word problems by manipulating a) the lexicaldifficulty of two words which were irrelevant for calculations and b) the numericaldifficulty of the word problem which was irrelevant for reading. We analyzed the meanfixation duration, which can be interpreted as an indicator for the cognitive effortduring processing of visual information (Strohmaier et al., 2020). If processes ofreading and calculating occur serially and in delimited mental representations, themanipulation should only affect the mean fixation duration of the varied words andnumbers.Analyses of the pilot data from N = 17 undergraduate students show that numericaldifficulty influences the mean fixation duration on numbers, but also on the remainingtext. Effects of lexical difficulty showed similar trends, but were not significant.Based on these results and additional data, we argue that eye movements indicate thatcognitive processes of reading and calculating overlap during word problem solvingand occur in a shared mental representation.