If you think a million dollars is hard enough to fathom, what about a trillion?
The world's richest man, Bill Gates could go from being a billionaire to the world's first trillionaire in just a matter of 25 years - that's as much as the GDP of Mexico!
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He's already worth $90 billion. In other words, if he were a country, he'd be the 63rd largest economy in the world.
The famously philanthropic Microsoft co-founder has donated more than $30 billion dollars to his charity.
But Oxfam has found that since 2009, the world's richest have benefited from an 11% annual rate of return, which puts him on track to be a trillionaire by the age of 86.
But some say, not so fast, noting Gates' wealth has only grown 4%, not 11% since he left Microsoft in 2006.
Gates and fellow billionaire friend Warren Buffet have both pledged to donate at least half of their fortunes.
At 86-years-old, Buffet may not reach trillionaire status in his lifetime, but that hasn't tapered his appetite for buying stocks.