EVEN for an economist, there are lots of very large numbers in the life of Ngozi Okonjo-Iweala. As the chair of Gavi, the vaccine alliance, she has overseen the annual immunisation of millions of children. When she was managing director of the World Bank, she oversaw US$81 billion (£58 billion) worth of operations. In her stints in charge of Nigeria’s finances, she tackled Africa’s most populous country’s US$30 billion debt. And she has 1,5 million followers on Twitter. There are lots of smaller numbers too: the 20 non-profit organisations that have appointed Okonjo-Iweala to their advisory boards, the major banks and corporations she has advised, the 10 honorary degrees in addition to her own doctorate, 20 or so awards, dozens of major reports authored, and the books. Then there are the multiple lists frequently featuring Okonjo-Iweala (66): the world’s 100 most powerful women, 100 most influential people in the world, 10 most influential women in Africa, Top 100 or 150 women in the world, and many others. On Monday, Okonjo-Iweala was added to a new list: that of director-general of the World Trade Organisation (WTO), a position that has never before been occupied by an African person nor by a woman. She will take over the institution, with its budget of US$220 million and a staff complement of 650, at a critical time. It will be the moment to put all the number-crunching experience she has gained over a 40-year career to use. The global trading system — with the WTO at its heart — is facing a make-or-break moment, say experts. But can Okonjo-Iweala fix it? Okonjo-Iweala was six when Nigeria gained its independence from Britain in 1960. She grew up in a small village in the country’s southern Delta State. Her parents, both distinguished academics, were studying in Europe on scholarships, so she and her six siblings were raised by a grandmother. Life was not easy. By the time she was nine, Okonjo-Iweala had learned to cook, fetch wood and manage many of the household tasks. The civil war pitting the separatist Biafra State against the Nigerian central government disrupted her education and exposed her to further hardship. “I was eating one meal a day and children were dying. So, I learned to live very frugally. I often say I can sleep on a mud floor as well as a feathered bed and be very comfortable. It has made me someone who can do without things in life because of what we went through,” Okonjo-Iweala told Forbes magazine last year. When her three-year-old sister became chronically ill with malaria, it was Okonjo-Iweala who carried her for 4,8km to the doctor’s surgery, pushing through a crowd of 600 and climbing through a window to get the treatment that saved the child’s life. At the end of the war, Okonjo-Iweala went to the United States to study economics at Harvard and MIT (Massachusetts Institute of Technology), married her childhood sweetheart and, at the age of 25, began working for the World Bank, rising steadily up the institution’s hierarchy, travelling widely, and only leaving when invited to be Finance