Abstract: An electronic calculator includes a mode selection key and a memo mode selection key. The mode selection key is actuated to select a memo mode for inputting and printing out memo data and a calculation mode for operating arithmetic calculation. The memo mode selection key is actuated to absolutely select the memo mode during the calculation mode. Once the memo mode selection key is actuated and a print key is actuated to print out the memo data, the calculation mode is reselected, automatically, so that the calculator can continue to calculate.