Why do americans pronounce numbers in a different way?

I'm new in the USA but i noticed right away that americans talk or say numbers differently. For example: the number 2400 (two thousand four hundred), instead they say... (twenty four hundred) I also notice this trend in the game show jeopardy.Why do americans pronounce numbers in a different way?
They are both correct, so what difference does it make? You could also say 240 tens.
Interesting observation. I'm American and never noticed that. Perhaps it's just verbal shorthand?Why do americans pronounce numbers in a different way?
It's the way languages develop differently.

Another difference... in UK we say two hundred and ten in US the say two hundred ten for the number 210

There are so many examples of the way numbers and words have developed in US and in other parts of the world.

It shows tyhe old saying "2 countries separated by a common language" I like that saying
Saves a syllable.Why do americans pronounce numbers in a different way?
I've noticed English say Zed, and Americans say Zee. Just an observation. Zed just sounds funny to me.