Portree used Portree's pier as a rest point. The town also began exporting fish at this time, which contributed greatly to the local economy. The town had the last manual telephone exchange in the UK, which closed in 1976. Portree shale is a geologic association in the vicinity of Portree, the existence of which is linked with potential petroleum occurrences of commercial importance. Portree Portree (; , ) is the largest town on Skye in the Inner Hebrides of Scotland. It is the location for the only secondary school on the island, Portree High School. Public transport services are limited to
Principal ideal is a principal ideal of formula_61, and formula_62 is a principal ideal of formula_63. In fact, formula_64 and formula_65 are principal ideals of any ring formula_2. A ring in which every ideal is principal is called "principal", or a principal ideal ring. A principal ideal domain (PID) is an integral domain in which every ideal is principal. Any PID must be a unique factorization domain; the normal proof of unique factorization in the integers (the so-called fundamental theorem of arithmetic) holds in any PID. Any Euclidean domain is a PID; the algorithm used to calculate greatest common divisors may be