I was trying to upgrade an older radio shack calculator to one somewhat larger.
John Murphy, Amazon
21 March 2013
Summary: The main issue is that it requires ambient low lighting to view, otherwise the background LED numbers come through and make viewing very difficult. I like my smaller radio shack calculator for ease of use and will only use the compucessory when (1) I cannot find my other calculator or (2) if I am in a viewing zone where the LED screen is perfectly attuned to the environment. In fairness I have no idea what dual power means.