Nigeria has the highest number of dollar-billionaires in sub-Saharan Africa.

This is if a new wealth report by Ventures Africa magazine is to be believed.

Of the 55 Africans who made the entry point of US$1bn, 20 of them are Nigerians. The Nigerians featured on the list include industrialist Aliko Dangote, who is listed as Africa’s wealthiest man with a reported $20.2bn fortune, and Globacom boss Mike Adenuga, who is listed as the third richest man in Africa with an $8bn fortune

Other Nigerians on the list include Folorunsho Alakija, the richest woman in Africa worth $7.3bn, and the CEO of Taleveras Group Igho Sanomi, who at 38 years old is listed as the youngest billionaire in Africa with a net worth of $1bn.

“That Nigeria has so many dollar-billionaires says something positive about our economy. As the saying goes, if you’re not doing business in Nigeria, then you’re not doing business in Africa,” said Ventures Africa publisher Chi-Chi Okonjo in a media statement.

The combined fortune of Africa’s 55 billionaires is $143.88bn. Two other women make the list: Isabel dos Santos, an Angolan investor who is also the daughter of Angola’s President José Eduardo dos Santos, and Ngina Kenyatta, the widow of Kenya’s first president.

The average net worth of the members of this exclusive club is $2.6bn while the median age of the richest people in Africa is 65 years.

After Nigeria, South Africa and Egypt lead the pack with the second and third highest number of billionaires at nine and eight respectively. Algeria, Angola, Zimbabwe and Swaziland only have one billionaire each. In all, there are 10 African countries represented on the list.

How was the list compiled?

In a separate media release, Ventures Africa shed some light on how it compiled its rich list.

“Our ranking of African billionaires is based on data compiled by Ventures Africa’s editorial team. We traversed Africa and beyond, seeking out immensely successful tycoons and business leaders who could possibly lay claim to a billion-dollar fortune. We looked through financial reports, tracked equity holdings around stock markets, identified specific shareholding structures in large, privately held companies and consulted with everyone from investment bankers to retailers and financial analysts to determine proper values for companies, real estate and other assets.

“For billionaires who hold their wealth through shares of publically traded companies, we calculated their fortunes using stock prices and exchange rates from the close of business on 6 September 2013. In cases where wealth is tied to privately held companies we ascertained the company’s value by using publically listed comparatives – usually companies of similar size, operating in the same industry in the same country. We used a range of metrics, including equivalent price-to-earnings or price-to-sales ratios, total value of assets or number of customers. For instance, when valuing Globacom, a leading Nigerian mobile telecommunications outfit wholly owned by billionaire Michael Adenuga, we benchmarked it against MTN Group, a pan-African mobile phone company listed on the Johannesburg Stock Exchange. We looked at the number of MTN subscribers vis-à-vis Globacom’s number.

“We divided Globacom’s total number of subscribers by MTN’s and multiplied it by MTN’s current market capitalisation. Then we crosschecked with investment bankers and other analysts to ensure our figure was fair. Every valuation we have done has been checked with our analysts. We have also accounted for art collections, jets, yachts, jewellery, cash and other investible assets.

“It is usually difficult to get billionaires who run private companies to divulge earning figures. But in cases where the billionaire or his or her associates provided these figures (or where we could obtain these figures form in-house sources), we adopted a conservative Earnings Before Interest Taxes Depreciation and Amortisation (EBITDA) multiple of five to reach a fair valuation.”