Here is a practical problem from a factory. There are illiterate workers who can not identify digits and do not know in which order they occur. They are supposed to fill cans with a certain weight of a given material. With a beam balance this is easy since a worker can place the required weight in one pan and keep pouring the material in another pan as long as the beam doesn't appear to be balanced. However, this factory uses digital weighing scales. What do you think is the easiest way to train the workers to do their job with a digital weighing scale apart from teaching them how to count or altering the digital weighing scale?
Note that the workers may be asked to fill a can with 3.1 kg of material, i.e. decimal fractions may be involved.