Everyone knows the tech industry is rich, but it can be challenging to get your head around just how much money it's minting.

Four of the industry's giants -- Facebook, Microsoft, Amazon and Google parent Alphabet -- reported unexpectedly large profits this week. (Amazon's profit more than doubled Thursday.) A fifth, Apple, releases earnings on Tuesday. These companies are the largest on Earth, at least in terms of their market value.

But their raw financial figures only tell you so much. Here are some facts you might not know about the lucre the technology industry is rolling in.

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1. Step aside, national economies

The five largest tech companies are collectively worth more than the entire economy of the United Kingdom. Investors value these companies at US$3.5 trillion; the gross domestic product of the U.K. was $2.6 trillion in 2017, according to the International Monetary Fund. Only four national economies are larger than the combined tech giants: those of the U.S., China, Japan and Germany.

The same five tech companies are worth more than the next 11 most valuable U.S. corporations, a list that includes JPMorgan Chase, Johnson & Johnson and Walmart.

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2. Earning multiples

Apple makes roughly as much money every day as 2500 average U.S. households can expect to see in a year. That's $151 million, a figure calculated from the company's expected profit in the January-March quarter and the median household income of $57,230 reported by the Census Bureau .

For a more prosaic comparison, Apple makes almost three times what ExxonMobil does; the oil giant had an average daily profit of $54 million last year.

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3. Facebook time

While you were looking at baby pictures or stalking your ex yesterday, Facebook made $1.6 million. The average user spends 42 minutes a day on the service, according to eMarketer estimates. Facebook's profits were almost $5 billion in the first quarter -- $56 million a day, $2.3 million an hour, $39,000 a minute.

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3. Big bucks, for free

The two big tech companies you almost never pay directly -- Google and Facebook -- can afford to offer you free services thanks to their hammerlock on digital advertising. The two will sell an estimated $61 billion in U.S. online ads this year, according to the research firm eMarketer.

That's more than a quarter of expected U.S. spending on all forms of advertising ($221 billion). All of it is in the hands of just two companies.

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4. Zuck's ups and downs

Mark Zuckerberg made $6.6 billion on Thursday, the day after Facebook reported earnings. The company's stock jumped 9 per cent on the news; the Facebook co-founder owned 457.1 million shares as of Dec. 31.

Of course, that cuts both ways. When Facebook's stock slid 8 per cent in a day after the Cambridge Analytica privacy scandal broke, Zuckerberg lost more than $6 billion.

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5. Instant cash

With a single move, Amazon could create $2 billion out of thin air. The company just said it will raise the annual price of its Prime membership program to $119 from $99. Given that there are now over 100 million Prime members -- and assuming they don't flee-- that's a good chunk of change for sliding a few digits around.

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6. If only

If you'd put $10,000 into Apple stock in September 1997 when co-founder Steve Jobs came back as CEO, your stake would be worth $2.1 million today.