3400
It is already rounded to the nearest hundreds.
3400
The question is ambiguous. For example, 3352.8 can be rounded to 3352.8 to the nearest tenth, 3400 to the nearest hundred, or 0 to the nearest ten thousands.
3400 is already at the nearest 100. Rounding to the nearest hundred means that the last two digits (tens and units digits) are replaced by 00 if they are between 1 and 49 (for example 5419 would be rounded to 5400), and if the last two digits are between 50 and 99, then the hundreds digit is increased by 1 followed by 00 (so 2456 would be rounded to 2500).
3400
3400
3500
3400
3400
3400
It is already rounded to the nearest hundreds.
3400
The question is ambiguous. For example, 3352.8 can be rounded to 3352.8 to the nearest tenth, 3400 to the nearest hundred, or 0 to the nearest ten thousands.
3000
8 is already rounded to the nearest 10th. Rounded to the nearest 10 is 10.
3400 is already at the nearest 100. Rounding to the nearest hundred means that the last two digits (tens and units digits) are replaced by 00 if they are between 1 and 49 (for example 5419 would be rounded to 5400), and if the last two digits are between 50 and 99, then the hundreds digit is increased by 1 followed by 00 (so 2456 would be rounded to 2500).