An AC adapter is included so you never have to worry about running out of power. However, if you want to travel, this calculator is also for you. It supports 2 AA batteries (not included), giving you the option of mobility. This is an adding machine and DOES NOT function like a standard desktop calculator. For example, to do the equation 4 – 2, you would need to press “4” then “+” then “2” then “-” then “equals” to get the right answer. Tutorials and examples are provided in the detailed instruction manual.