Spanx inventor Sara Blakely, who joined the rich list in 2012, is the youngest at 42.

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Spanx, panties that help make a woman look more shapely, have made entrepreneur Sara Blakely a billionaire.

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Spanx inventor Sara Blakely, who joined the rich list in 2012, is the youngest at 41.

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Fifty years later, the girdle-like Spanx is back thanks to Sara Blakely, a brilliant woman who built a multimillion empire.

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Just over a decade ago, Sara Blakely was shilling her invention, a modernized girdle, from a folding table in the foyer of Neiman Marcus.

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When I wrote a Forbes profile on Sara Blakely last year, I included a long list of competitors that have flooded the market since she launched her Spanx shapewear brand in 2000.

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