E-Day is celebrated on February 7 in the United States, marking the significance of the mathematical constant e, which is approximately 2.718281828. The date 2/7 corresponds to the first two digits of e when rounded to the nearest tenth. This holiday highlights the importance of e in mathematics, particularly in relation to logarithmic and exponential functions. While the exact origins of E-Day are unclear, it gained popularity after a University of Portland student noted the numerical coincidence in 2018, leading to increased discussions among math enthusiasts. Participants often engage in educational activities related to mathematics, especially focusing on the properties and applications of the constant e.