Microsoft founder Bill Gates has been one of the world’s richest men for more than 20 years.

In 1987 at the age of 31 he became the world’s youngest billionaire. By 1995 he was the richest person in the world, with a fortune of $13billion.

Now 62, he tops the 2017 Forbes ranking of world billionaires, with the publication estimating his wealth to be around $89billion, up from $84.5billion the year before.

Of course, without access to their bank statements and accountants, it’s difficult to say exactly how much cash the rich and privileged have, so publications differ in their guesses about individuals’ worth.

The Sunday Times Rich List thinks Gates is worth a little more – at £70.8billion ($97billion).

And the Bloomberg Billionaires List currently estimates his wealth as $93.9billion

But Gates may have competition this year from Amazon founder Jeff Bezos . Forbes’ live list currently has the 54-year-old as richer than Gates, with an estimated fortune of $108billion.

How did he make his fortune?

Gates became a talented programmer on computers while at school. In 1975 he dropped out of Harvard and founded Microsoft along with friend Paul Allen.

The company would develop the DOS operating system for IBM’s first PC, and by 1985 released the first version of Microsoft Windows.

His vision for the firm was famously to put “a computer on every desk and in every home.”

Microsoft dominated the computer software market for decades, and made him a billionaire after the firm floated on the stock exchange in 1986.

Gates stepped down as chairman of Microsoft in 2014, but remains on the company’s board.

But he is still one of the highest-earning billionaires in the world, thanks to his stake in Microsoft and investments through his private firm Cascade Investment.

What’s he doing with all that money?

Gates’ first big purchase with his Microsoft money in the 1970s was a Porsche 911.

Decades later, he now lives in a $125million 66,000-sq ft high-tech mansion in Washington, US.

Since stepping down at Microsoft, he has devoted a lot of his time to charity through the Bill and Melinda Gates Foundation, which he runs with his wife.

The foundation is dedicated to funding health and education projects, and aims to eradicate deadly diseases such as polio and malaria.

It is the largest philanthropic organisation in the world, with an endowment of more than $40billion, and makes grant payments of more than $3billion a year.

In January 2018 he revealed a £29million investment in a bid to develop a “supercow”.

Will his kids inherit the wealth?

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Gates has famously declared the majority of his fortune will go to charity, rather than family.

Bill said his three children – Jennifer, Phoebe and Rory – would instead be given the very best education in their early years to prepare them for a good career.

He told This Morning in 2016: “Our kids will receive a great education and some money so they are never going to be poorly off but they’ll go out and have their own career.

“It’s not a favour to kids to have them have huge sums of wealth. It distorts anything they might do, creating their own path. This money is dedicated to helping the poorest. They know that, they are proud of that.”

What has he said about being rich?

He told students at the University of Washington in 2011: “Wealth above a certain level really is just, it’s a responsibility that then you’re going to have to either a) leave it to your children, which may not be good for them or b) try and be smart about giving it away. I can understand wanting to have millions of dollars.

“There’s certain meaningful freedom that comes with that but once you get much beyond that, I have to tell you, it’s the same hamburger.”