HOW much is $188 trillion? It's one of those numbers that is so incomprehensible the answer almost doesn't matter; it's like saying, "If you won £25m on the Lottery tomorrow, what would you do?".

The answer to each question is invariably prefaced with bewilderment, a slightly startled expression and a delayed, almost hesitant, response. "Well, I...er..."

If we're looking to see who makes serious money from the sports business, a further examination as to how this colossal number is arrived at goes a long way to providing us with the answers. Incidentally, if you have children, you may wish to sit down before reading any further.

A new book, due to be published next month examines the relationship of children, defined as "tweens", i.e. 8 to 14-year-olds, and commercial brands.

The book contains some amazing facts, garnered from research undertaken in 15 countries. For example, it estimates that an average child in the UK will watch between 20,000 and 40,000 television commercials a year, that's around six and a half hours of advertising a week.

Tweens are described as "the richest generation in history" whose spending has doubled every decade since the 1960s.

But, as every parent knows, apart from spending their "own" money, children assert massive influence on how a significant proportion of household income is spent. Globally, tweens influence an astonishing $188 trillion of all household expenditure.

These influences have ensured that the world's largest sports-related businesses have grown at an amazing rate, courtesy of the tween market.

The sports goods manufacturers, Nike and Adidas, are considered by tweens to be the world's leading brands. When the Reebok brand is added, it is easy to see how the value of these three companies has grown by £1.7 billion in the last six months alone.

And driving the profile of each brand is sport: 42 per cent of all boys aged 8-14 consider a brand to be "really cool" if its advertising features a sports star.

The appearance of a sports star far outstrips any other category of star when the "coolness" of a brand is considered.

As the authors explain, "Tiger Woods was picked up by Nike in 1991 when he was a young pro on the golfing circuit. Now he is a megastar, attracting millions of fans to the Nike brand."

Nike and its peers in the sport business continue to expand at rates that surpass, by some distance, teams the companies sponsor.

The combined value of Nike, Adidas and Reebok, now exceeds £11.5 billion. Contrast this with the combined worth of Europe's most valuable football clubs.

The continent's top ten, in terms of value, would comprise clubs of the stature of Manchester United, Bayern Munich and Real Madrid, yet the total value of Europe's top 10 clubs is around one tenth that of the sports wear manufacturers.

No wonder Nike can afford to pay Manchester United £303m for the licence to produce the club's kit. It's the same reason why Reebok can pay Liverpool £100m over the next six years to be the club's 'premier sponsor': branding.

Such thinking explains why those of us who don't live in Manchester or Liverpool are sometimes bewildered when a youngster walks past us wearing a shirt belonging to one or other team (emblazoned with the sponsor's name) when a perfectly good local option exists.