Odd-even rationing
Encyclopedia
Odd-even rationing is a method of rationing
in which access to some resource is restricted to half the population on any given day. In a common example, car
s are allowed to drive
or to purchase gasoline
on alternate days, according to whether the last digit in their license plate is even or odd. Similarly, during a drought
, houses can be restricted from using water outdoors
according to the parity of the house number
.
One issue with odd-even rationing by day is that two "odd" days in a row occur whenever a month ends on an odd-numbered day.
; indeed, half of the numbers in a given range end in 0, 2, 4, 6, 8 and the other half in 1, 3, 5, 7, 9, so it makes sense to include 0 with the other even digits for rationing.
Nonetheless, the parity of 0 has caused confusion. The relevant legislation sometimes stipulates that zero is even. In fact, an odd-even restriction on driving in 1977 Paris
did lead to confusion when the rules were unclear. On an odd-only day, the police avoided fining drivers whose plates ended in 0, because they did not know whether 0 was even.
Rationing
Rationing is the controlled distribution of scarce resources, goods, or services. Rationing controls the size of the ration, one's allotted portion of the resources being distributed on a particular day or at a particular time.- In economics :...
in which access to some resource is restricted to half the population on any given day. In a common example, car
Čar
Čar is a village in the municipality of Bujanovac, Serbia. According to the 2002 census, the town has a population of 296 people.-References:...
s are allowed to drive
Road space rationing
Road space rationing is a travel demand management strategy aimed to reduce the negative externalities generated by peak urban travel demand in excess of available supply or road capacity, through artificially restricting demand by rationing the scarce common good road capacity, especially...
or to purchase gasoline
Gasoline
Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...
on alternate days, according to whether the last digit in their license plate is even or odd. Similarly, during a drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
, houses can be restricted from using water outdoors
Outdoor water-use restriction
An outdoor water-use restriction is a ban or other lesser restrictions put into effect that restricts the outdoor use of water supplies. Often called a watering ban or hosepipe ban, it can affect:*irrigation of lawns*car washing...
according to the parity of the house number
House numbering
House numbering is the system of giving a unique number to each building in a street or area, with the intention of making it easier to locate a particular building. The house number is often part of a postal address....
.
One issue with odd-even rationing by day is that two "odd" days in a row occur whenever a month ends on an odd-numbered day.
U.S. gasoline rationing
Odd–even rationing was instituted in the U. S. as part of the response to the second gas crisis in 1978, when turbulent conditions in Iraq and Iran led to worldwide oil price increases, even though a supply shortage did not materialize in the U. S.Dealing with 0
Zero is an even numberEvenness of zero
Zero is an even number. In other words, its parity—the quality of an integer being even or odd—is even. Zero fits the definition of "even number": it is an integer multiple of 2, namely...
; indeed, half of the numbers in a given range end in 0, 2, 4, 6, 8 and the other half in 1, 3, 5, 7, 9, so it makes sense to include 0 with the other even digits for rationing.
Nonetheless, the parity of 0 has caused confusion. The relevant legislation sometimes stipulates that zero is even. In fact, an odd-even restriction on driving in 1977 Paris
Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...
did lead to confusion when the rules were unclear. On an odd-only day, the police avoided fining drivers whose plates ended in 0, because they did not know whether 0 was even.