400
400 is rounded to the nearest hundreds which will be 500 and you can line them up straight since your rounding to the nearest 100 you'll add 1 + 4 = 5 and 0 + 0 = 0 and 0 + 0 = 0 and your answer is 500.
Any number in the interval [350, 450].
350 to 449
It rounds to 300
400
It rounds to 400
400
400
379 rounded to the nearest hundred is 400:)
400
400
It could be 599, rounded to the nearest 400.
400
400
380 rounded to the nearest 10th 400 rounded to the nearest 100th