If you are rounding to hundreds, yes.
449
Anything from 350 to 449
It is 450.
400
It is 400.
The greatest whole number to round to 300 would be 449 rounded to the nearest 300
449
Anything from 350 to 449
449
It is 450.
400
400
The hundreds, on either side of 449 are 400 and 500. 449 is 49 away from 400, and 51 away from 500. So the nearest hundred is 400.
400
500
The Greatest Common Factor of 189 and 449 is 1.
It is 400.