Uzbekistan is central Asia's most populous state and strives to assert itself as a regional power.
And in the US, though breast pumps, vasectomies and artificial teeth are sales tax-exempt and tax-deductible medical care, tampons are not even exempted from sales tax in some states (including California and New York, two of the most populous states).
Buhari - who said he was "very confident" of victory - has campaigned as a born-again democrat intent on cleaning up the corrupt politics of the continent's biggest economy and most populous nation.
Boko Haram's campaign to impose a medieval Islamic caliphate on Africa's most populous nation has killed more than 3,000 this year.
Whenever it happens, the fourth election since the end of military rule in 1998 will be the biggest test of whether Africa's most populous nation can hold democratic elections after decades of rule by the gun, bribery and intimidation.
The Nigerian government announced on Friday that it had agreed a ceasefire with Boko Haram, a deal that would mark a major breakthrough after a five-year insurgency by extremists seeking to create an Islamic state in the north of Africa's most populous country.
This war of words also reveals the simmering potential of armed groups to derail democracy in Africa's most populous nation.
The former army general has campaigned as a born-again democrat intent on cleaning up the corrupt politics of the continent's largest economy and most populous nation.
According to the Safe Cities Index, put together by the Economist's Intelligence Unit (EIU), the title of world's safest goes to the city that is also the most populous: Tokyo.
Birmingham, Britain's second most populous city, comes joint-second with Liverpool, the recent European capital of culture – six episodes have been broadcast from each.
Long-term, there are plans to expand beyond Africa's most populous country.
