When rounding to a specific place, take a look at the digit immediately to the right of the target, in this case, the tens place. If that digit is 4 or less, zero everything to the right of the target out. If that digit is 5 through 9, increase the target by one and zero everything to the right of it out. If the target is a 9, increasing it will turn it to zero and increase the digit to the left of the target by one.
It is 450.
372 rounded to the nearest hundred is 400
4198 to the nearest 100 = 4200
The answer is zero.
387 to the nearest 100 is 400.
It is 400 because 402 is less than 450
It is 450.
round 90 to the nearest ten
372 rounded to the nearest hundred is 400
300
The tens value is zero, so it rounds down, giving 400.
100
100
100
400
10100
4198 to the nearest 100 = 4200