Mexican tycoon Carlos Slim may be the world’s richest man but he limits his monthly salary to $24,000 and travels in a Suburban, according to his biography.

Mr Slim, 70, knocked Bill Gates form the top of the Forbes list of the world’s billionaires this year with an estimated fortune of US$53.5 billion.

He began his business career aged 10, selling sweets and drinks to his family and later made his name with aggressive investments during crises.

‘Unlike aristocrats, the jet set or the monarchy, he’s extremely simple,’ biographer Jose Martinez told AFP as a new edition of his 2002 book, ‘Carlos Slim, unpublished portrait,’ was set for release across Latin America.

According to his biographer, Mr Slim’s fortune far exceeds the amount calculated by Forbes.

The fifth of six children – three boys and three girls – Mr Slim was born into a well-off family, including a Lebanese immigrant father, in Mexico City in January 1940.

Mr Slim studied civil engineering and later built up the telephone monopoly Telmex after acquiring it from the government in 1990.

He hit the top spot of billionaires after his fortune rose US$18.5 billion in 12 months, and shares of America Movil, of which he owns a US$23-billion stake, were up 35 per cent in a year, according to Forbes.

Last year he injected US$250 million into the ailing New York Times, becoming its second biggest partner and surprising some in the media.