International Journal of Neutrosophic Science IJNS 2690-6805 2692-6148 10.54216/IJNS https://www.americaspg.com/journals/show/2756 2020 2020 College of Engineering and Technology, American University of the Middle East, Egaila 54200, Kuwait. Aslı Aslı Department of Mathematics, ˙Izmir University of Economics, ˙Izmir, Turkey. G. Yazgı Tutuncu Fuzzy concepts have been widely used to treat imprecision in many fields of natural and social sciences. In most of the natural science fields such as applied mathematics, physics, chemistry, and engineering, triangular and trapezoidal fuzzy numbers are commonly used and arithmetic operations on those numbers are studied in detail. On the other hand, in engineering and social science fields such as sociology and psychology, while treating the uncertainties, these numbers are not applicable and fuzzy numbers with more parameters and clear definitions of their arithmetic operations are needed. In order to fill this gap in the literature, in this study we propose the generalized pentagonal fuzzy numbers, and we define fuzzy arithmetic operations based on both extension and the function principle. 2024 2024 187 197 10.54216/IJNS.240216 https://www.americaspg.com/articleinfo/21/show/2756