Numbers in writing

[Mihai_alexandru]

How do we use numbers in writing? Should we use words to write them down or digits? To be more explanatory:

"I bought 3 apples from the market yesterday."

or

"I bought three apples from the market yesterday."

In my language, I know that, in literature, you have to write the numbers from 0 to 9 in letters and the rest of them in digits. Do we also use this rule in the English language? Thank you in advance for your help.

[Snowcake]

Some authorities say that the numbers one through nine or ten should be spelled out and figures used for higher numbers. Other authorities spell out one through one hundred, plus even hundreds, thousands, and so on. The best strategy is to be consistent. Correct Examples: I want five copies, not ten copies.
I want 5 copies, not 10 copies.

For further rules see here Rules for Writing Numbers

and here Writing Numbers

[Mihai_alexandru]

Thank you very much for your help. I now understand the correct usage of numbers in English writing. I only have one more curiosity that I would like to know on this subject. It is about American English:

$23.50 means 23 dollars and 50 cents?

[Snowcake]

Yes. You're right.