Which number round to 38,800 when rounded to the nearest hundred

There can be so many of such.

Eg.  38 750              38 835

       38 795       

       38 820

Any of the numbers above when rounded to the nearest hundred would result in 38 800.

The idea is such that to make sure the 100 digit is 7 and the 10 digit is  5 or more.

Or if the 100 digit is already 8, then the 10 digit must be less than 5

There are many numbers that could round to 38,800 when rounded to the nearest hundred. I assume you probably have some choices, if you posted those I could tell you which one it is. But for now I can show you some examples:
38,789
38,756
38,819
38,807