900,000 is the nearest 'hundred thousand'.
872768 = 872,768 .
This is read as ' eight hundred and seventy two thousand, seven hundred and sixty eight '.
To convert to the 'nearest'.
The left hand '8' is eight hundred thousand'.
The next '7' is seventy thousand.
If this number is '5' or greater , '7' in this case, then you add '1' to the 'given nearest number' , '8' is this case. So 8 + 1 = 9
So the answer is 900,000 ( nine hundred thousand).
NB The remainder of the numbers to the right can be ignored.