Just how many Nigerians are there? And which half of Africa's most populous country, north or south, has more people?
The answers to these questions will be almost impossible to find without starting a riot. The sheer size of the task as well as the bitter political and religious divisions threaten to sabotage the process.
Nigeria is holding its first census for 15 years, and at current estimates its population is anything between 120 and 150 million. The Government and businesses say they need more accurate figures, and have persuaded the EU and other international donors to contribute more than half of the £150m it will cost to get the count.
"If you want to develop your country, you need to know how many people there are there," said Femi Fani-Kayode, a presidential spokesman. "This is purely for economic purposes."
Ethnicity and religion have been left out of the census because, the government insists, the purpose of the survey is purely economic. However, many believe it is reluctant to tackle such divisive issues. Nigeria has roughly 250 ethnic groups, each demanding a voice in the politics of the country. It is also divided approximately in half - between Muslims in the north and Christians and traditional religions in the south.
Last month, more than 150 people were killed in religious violence after the publication of the Danish cartoons depicting the Prophet Mohamed. Since the country's return to civilian rule in 1999, unrest has left 20,000 dead.
The headcount comes at a time of increased political tension throughout the country. With national elections next year, the three main ethnic groups - Yoruba, Hausa, and Igbo - are vying for control of the state, each fearing domination by the others.
Governments in the past have been accused of manipulating figures for political ends - the distribution of federal government funds to Nigeria's 36 states is largely based on population figures.
President Olusegun Obasanjo comes from southern Yoruba group, who are now reluctant to relinquish the power and control he has given them. However, since independence in 1960, the country's ruling elite has been dominated - through a succession of coups and elections - by the northern Hausa, who would like power returned to them.
In the south-east, the Igbo ethnic group have threatened to boycott the census. In 1970 they lost a war of independence against the Nigerian state - the Biafran war, in which over a million people were killed - but the idea of Biafra has had a resurgence in recent years, and in boycotting the census, the Igbo wish to distance themselves from the rest of Nigeria.
Chidi Chidi, a spokesman for the Biafran Igbo separatists, said: "We are not Nigerians - we don't want to be counted. We will do our own count when the time comes. There is no way they'll give the real figure - they will manipulate them."
In numbers comes strength, and the fear is that for one group to have more people, other groups would become politically weakened and therefore may resort to violence to reassert their influence.
The National Population Commission must also try to deal with the practicalities of a census in a country that is nearly four times the size of Britain, but has half the number of roads. Some areas - such as the swamps of the southern-eastern Niger Delta region - can be almost inaccessible.Reuse content