Philips had already started developing chips that would convert the 14 bits into analog signals. This brought both parties close together on this point. It is not only the number of bits with which the variations in voltage are recorded that is of importance for the quality, because sometimes bits are read incorrectly, for example as a result of an error in the surface of the disc. This gives an incorrect sound which cannot be masked. It is annoying in pieces of music, but it would be fatal when recording computer files.
Incorrect bits render a computer program useless.
Application in computers was still a long way off, but even then they were already starting to think how the CD could be used for the computer. It was therefore important to agree upon a watertight technique for detecting errors. This is also done with credit card numbers, for example. The last figure is actually superfluous, but it serves as a check. It is chosen in such a manner that addition of the figures in a specific way gives an exact multiple of 10.