645.9 rounded to the nearest one (1 whole place) = ?
How is the number rounded off? Half Up, Half Down, Half Away From Zero, Half Towards Zero, Half to Even, Half to Odd. To Ceiling, To Floor.
Rounding a number means replacing it with a simpler, shorter approximation, while keeping its value close to the initial one. The rounded number will be less accurate, but easier to work with.
How is the number rounded off? Explanation.
Counting by units (1 whole place at a time), our number is sitting on the axis of numbers between two consecutive neighboring numbers:
645 < 645.9 < 646
Our number is to be rounded off to one of these neighbors, the closer one.
The middle of this interval, the number that is equally close to the either neighbor, is: (645 + 646) ÷ 2 = 645.5
Our number, 645.9, is larger than 645.5, so it is closer to the larger neighbor: 646
Except for 'To Ceiling, To Floor', the rounded off number (both the positive and the negative) will be equal only to this larger neighbor.
Rule of thumb:
Rounding digit. Let's call the digit of the position place that is intended to round off to as the 'rounding digit'. The digit is 5: 645.9
In a positive number, if the digit to the right of the 'rounding digit' is larger than 5, then the number is rounded to the larger neighbor.
The digit is 9: 645.9 ≈ 646 rounded to the nearest one (1 whole place).
Or, even simpler.
In any number rounded to whole places, if the digit to the right of the 'rounding digit' is 5 (but it is not the last non-zero digit to the right) or more than 5, ie. 6, 7, 8 or 9, then increase the 'rounding digit' by 1 and replace all the digits to the right of it with zeros:
645.9 ≈ 646 rounded to the nearest one (1 whole place)
Below we round off both the positive and the negative:
Half Up, Half Down, Half Away From Zero, Half Towards Zero, Half to Even, Half to Odd. To Ceiling, To Floor.
Number Round Half Up:
Numbers that are halfway between two neighbors are rounded off to the larger neighbor. 645.9 is not halfway between its neighbors.
645.9 ≈ 646
- 645.9 ≈ - 646
rounded to the nearest one (1 whole place)
Number Round Half Down:
Numbers that are halfway between two neighbors are rounded off to the smaller neighbor. 645.9 is not halfway between its neighbors.
645.9 ≈ 646
- 645.9 ≈ - 646
rounded to the nearest one (1 whole place)
Number Round Half Away From Zero:
Numbers that are halfway between two neighbors are rounded off to the neighbor which is farther away from zero. 645.9 is not halfway between its neighbors.
645.9 ≈ 646
- 645.9 ≈ - 646
rounded to the nearest one (1 whole place)
Number Round Half Towards Zero:
Numbers that are halfway between two neighbors are rounded off to the neighbor which is closer towards zero. 645.9 is not halfway between its neighbors.
645.9 ≈ 646
- 645.9 ≈ - 646
rounded to the nearest one (1 whole place)
Number Round Half to Even:
(Gaussian Rounding or Banker's Rounding)
Numbers that are halfway between two neighbors are rounded off to the neighbor with an even rounding digit. 645.9 is not halfway between its neighbors.
645.9 ≈ 646
- 645.9 ≈ - 646
rounded to the nearest one (1 whole place)
Number Round Half to Odd:
(Gaussian Rounding or Banker's Rounding)
Numbers that are halfway between two neighbors are rounded off to the neighbor with an odd rounding digit. 645.9 is not halfway between its neighbors.
645.9 ≈ 646
- 645.9 ≈ - 646
rounded to the nearest one (1 whole place)
Number Round Ceiling:
All the numbers that are between two neighbors are always rounded off to the larger neighbor.
645.9 ≈ 646
- 645.9 ≈ - 645
rounded to the nearest one (1 whole place)
Number Round Floor:
All the numbers that are between two neighbors are always rounded off to the smaller neighbor.
645.9 ≈ 645
- 645.9 ≈ - 646
rounded to the nearest one (1 whole place)
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