What was the first digital scale?
Weighing scale
The balance (also balance scale, beam balance and laboratory balance) was the first mass measuring instrument invented.[1] In its traditional form, it consists of a pivoted horizontal lever with arms of equal length–the beam–and a weighing pan[7] suspended from each arm (hence the plural name "scales" for a weighing instrument). The unknown mass is placed in one pan and standard masses are added to the other pan until the beam is as close to equilibrium as possible. In precision balances, a more accurate determination of the mass is given by the position of a sliding mass moved along a graduated scale. Technically, a balance compares weight rather than mass, but, in a given gravitational field (such as Earth's gravity), the weight of an object is proportional to its mass, so the standard masses used with balances are usually labeled in units of mass (e.g. g or kg).
Stepped reckoner
The step reckoner (or stepped reckoner) was a digital mechanical calculator invented by the German mathematician Gottfried Wilhelm Leibniz around 1672 and completed in 1694. The name comes from the translation of the German term for its operating mechanism, "Staffelwalze", meaning 'stepped drum'. It was the first calculator that could perform all four arithmetic operations. 