An infinite amount, because 200 could be closer to any number than any other number, and therefore you round to 200. It all depends what other number you choose and what number you are starting at. Say you are rounding from 4000 and to either 200 or 2,534,592; you will round to 200 because it is closer, and following that logic, many other numbers round to 200. In fact, an infinite amount do.
Ten whole numbers round to 50, if you include 50 itself which requires no rounding.
Three.
how many numbers round to 300
There are an infinite list of different numbers, but only 90 of them are integers (whole numbers).
55
Ten whole numbers round to 50, if you include 50 itself which requires no rounding.
An infinite number.
1000 numbers. From 19,500 to 20,499 all round to 20,000
430
Three.
Infinite
how many numbers round to 300
All of them. Different numbers have different numbers of factors.
There are an infinite list of different numbers, but only 90 of them are integers (whole numbers).
500
Four of them.
55