Microsoft founder Bill Gates will have his last official day at the company on Friday.

A Harvard University dropout, Gates found Microsoft with Paul Allen in 1975, steering it to become the most successful software company in the world.

After he leaves the company on Friday, Gates will remain on as chairperson of the board of Microsoft, but will focus most of his attention on his charity organisation, The Bill and Melinda Gates Foundation.

Bill Gates was listed as the richest man in the world by Forbes for 13 years, only recently being eclipsed by Warren Buffett and Mexican telecom titan Carlos Slim Helú.

Gates' personal net-worth is currently estimated to be $58-billion.

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