Hundreds are the numbers, simply put, with at least two zeroes at the end.
17. 800 and 900, which are the closest numbers with at least two zeroes at the end to 848.
Continue doing it like this.
18. 500 and 600
19. 500 and 600
20. 72,914,900 and 72,915,000
21. 725,500 and 725,600
22. 400 and 500
23. 76,500 and 76,600
24. 1,108,700 and 1,108,800
25. 3,572,200 and 3,572,300
26. 702,900 and 703,000
27. 40,493,500 and 40,493,600
28. 500 and 600