10000
When rounding 9990 to the nearest hundred, the answer could either be 9900, or 10,000. Since the tens digit is a 9 (9990) you round up, meaning you get 10,000.
10000
one million
10,000
9990
9990
10,000
10000
10000
0
80,000 is already rounded to the nearest hundreds.
500
0
0
3571000
2600