I agree with Greg -- almost everyone will always say "five thousand six hundred and sixty." The other option is possible, but much more rare, especially for large numbers. We will say the number differently, though, if it refers to something like a room number, a locker number, an ID number, a phone number, or any other number that is just a label and not an actual quantity. In these cases, we usually split the number into two-digit sets: "fifty-six sixty." ("I'm staying in room fifty-six sixty." "Your locker is number fifty-six sixty." "My phone number is one-seven-four, fifty-six sixty.")

US: It depends on what it is. I would likely say any of the following: "Fifty-Six, sixty" "Fifty-six hundred, sixty" "Five thousand, six hundred, sixty" "Five, Six, Six, Zero" (or "Five, Six, Six, Oh") "Five Six Sixty." I was taught *not* to say "and" when saying numbers. So, "Five thousand, Six hundred, and Sixty" sounds very, very wrong to me. (Native, but wrong.)

Almost always, Five thousand, 6 hundred and sixty. For a large number like this, you only rarely will hear it as fifty six hundred and sixty. A smaller number in the single thousands, like 1360 you would hear the 'hundreds' form more often. But even here, the form "One thousand three hundred and sixty" is more common.

Five thousand-six hundred-sixty OR fifty-six hundred and sixty.

Different English speaking countries same them differently. Both Carlos and Tara are correct. Pick whichever you like