Be certain with your calculations with Double Check Function The compact size allows the P170-DH -3 to fit on your desktop without taking up too much space. This unit is packed with important business functions such as the ability to calculate your cost, selling price or profit margin with the touch of a few keys. Be certain with your calculations with Double Check Function The compact size allows the P170-DH -3 to fit on your desktop without taking up too much space. This unit is packed with important business functions such as the ability to calculate your cost, selling price or profit margin with the touch of a few keys.