Oh, dude, you just look at the hundreds place, which is 6. Since it's greater than 5, you round up to the next thousand. So, 7649 rounded to the nearest thousand is 8000. Easy peasy, like basic math stuff, you know?
7600
80,000 is already rounded to the nearest hundreds.
500
0
0
0
3600
8500
3571000
6248000
2600