What is 25 rounded to the nearest whole number?

Answer 1

Commonly 0.5 gets rounded up. So it would be 3

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That is the commonly accepted view and it is popular with schools because it is a simple rule. Easy to explain, easy to use. Unfortunately, this method introduces an upward bias but there is an accepted method that gets around this problem which would give the answer 2.

In the commonly accpted method,

• if the last digit is 0, you don't need to do any rounding,
• If the last digit is 1, 2, 3 or 4 you round down,
• If the last digit is 5, 6, 7, 8 or 9 you round up.

So, in the long run you round up more often than you round down and that is what creates an upward bias. So what you need is a system where you

• with 1, 2, 3 or 4 round down,
• with 6, 7, 8 or 9 round up, and
• with 5, round up half the time and round down half the time.

One way of ensuring that is to round 5 to even. This is in accordance with the IEEE (Institute of Electronic and Electrical Engineers) standard 754. For more, see the link.

Answer 2

The number 2.5 has both the integer and a fraction part. Rounding off 2.5 to the nearest whole number would be 3 because any number that is between 2.5 and 2.9 must be rounded up to 3.

Answer 3

25 is, itself, a whole number.

Answer 4

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