Math fluency is the ability to efficiently solve known arithmetic exercises, and it is one of the building blocks for academic achievements and daily use. Math fluency is assessed by how many exercises individuals can solve correctly in a limited time, requiring switching from one exercise to another. Switching is one of the executive functions and involves flexibility and adaptation to changing circumstances. Switching is measured through switch cost, which represents the difference in performance between executing the same task sequentially and switching between tasks. The current study examines the switch cost in math fluency. Participants, students from higher academic institutions, performed a math fluency test applied by the Ben-Gurion University Math Fluency (BGU-MF) tool, which included simple arithmetic exercises of addition, subtraction, multiplication and division. In Experiment 1, we examined the switch cost for each operation, and between pairs of operations, among 135 students (age 19 to 34). Results showed that the switch cost differs among different operations. Moreover, switch costs occur when alternating between complementary operations, but not between operations that rely on the same cognitive mechanisms, such as retrieval or calculation. In Experiment 2, we examined the switch cost in math fluency among 54 students (age 21 to 34) with high- vs. low- math anxiety. High math anxiety participants presented poorer performance in math fluency, as measured by accuracy rates and reaction times, and a larger switch cost. Our results fit the Attentional Control Theory (ACT) which suggests that anxiety impairs the executive functions. The effects of dominance, familiarity, difficulty, mental sets and executive functions on the switch cost in math fluency are discussed.