How do you write a trillion?

This question actually has two answers, which depends on what number scale you're using. In one number scale (called short scale) a trillion is a one followed by 12 zeros:
1,000,000,000,000
In the second number scale (called long scale) a trillion is a one followed by 18 zeros:
1,000,000,000,000,000,000

The way to identify which number scale you're working with is by counting out numbers in sets of three zeros. In the short scale we have the following progression:
1000 - One thousand
1,000,000 - One million
1,000,000,000 - One billion

In the long scale we have this progression:
1000 - One thousand
1,000,000 - One million
1,000,000,000 - One thousand million (or milliard)

So if the term "thousand million" or "milliard" are foreign to you, you're on short scale. Otherwise you're on long scale.

1,000 thousand
1,000,000 million
1,000,000,000 billion
1,000,000,000,000 trillion

1'000'000'000'000'

easier written in sci notation

10^12




.

One trillion
(1,000,000,000,000)

That depends,

in western part, they wrote 1,000,000,000,000.00

in Asian or non-western numeric rule, it's 1.000.000.000.000,00

It actually depends on where you're from. Everybody agrees that a million is:

1,000,000 (although we disagree how to punctuate it).

Beyond that, the Americans and British, for example, disagree on the term. In the U.S., a billion is 1,000 million, or

1,000,000,000,

whereas in England, a billion is a million million, or

1,000,000,000,000.

Now in the U.S. the above number is a trillion, or 1,000 billion. But a trillion in England is a million billion, or

1,000,000,000,000,000, which of course is a quadrillion in the States.

Generally, after a million, the British n-illion is worth 1,000 times as much as the U.S. n-illion.

TRee Lion

1,000,000,000,000
= a million million
= 10^12

10^12=1'000'000'000'000