the calculators are powered by four aaa batteries used for primary power. it also uses one lithium battery cr2032 for a memory backup when the primary power is down. all program memories will be deleted if both primary power and memory backup power are removed or down. the calculators consume power at the rate of 0.2 w. based on the manufacturer's data sheet, zinc-carbon r03 aaa batteries and alkaline lr03 batteries can supply power for 140 hours and 230 hours for continuous display of main menu. the back-up battery can operate for about two years.