Versatile twin-powered calculator with adding machine logic.Solar powered with battery backup prevents memory loss and keeps calculator running in all lighting conditions.Easy-to-read display with automatic three-digit punctuation.Auto power off after seven minutes.Versatile twin-powered calculator with adding machine logic. Solar powered with battery backup prevents memory loss and keeps calculator running in all lighting conditions. Easy-to-read display with automatic three-digit punctuation. Auto power off after seven minutes.