Early versions of the UNIVAC 1106 were simply half speed UNIVAC 1108 systems. Later Sperry Rand used a different memory system which was inherently slower and cheaper than that of the UNIVAC 1108.
When Sperry Rand replaced the core memory with semiconductor memory, the same machine was released as the UNIVAC 1100/10. In this new naming convention, the final digit represented the number of CPUs (called CAUs) in the system.