How do you round to the nearest whole number using decimals?

Answer 1

To round a number to a particular digit, look at the digit immediately to the right of your target, in this case, the tenths place. If that digit is 4 or lower, zero it and everything to the right of it out. If that digit is 5 or higher, increase the target digit by one and zero everything to the right of it out. If your target digit is a 9, increasing it will turn it to zero and increase the digit to the left of it by one.

Answer 2

If the fractional part is less than 0.5 you just delete it.If the fractional part is greater than 0.5 then you increase the integer part of the number and delete everything at or after the decimal point.

If the fractional part is exactly 0.5 then, if the last digit of the integer part is even, you leave that as it is and delete everything at or after the decimal point; while if it is odd, you increase it by 1 [so that is it even], and delete everything at or after the decimal point.

This may be at odds with school teaching of rounding 5 up every time but that rule is faulty since it introduces an upward bias. The rule, given above, "round up or down so that the new last digit is even" is consistent with the default rounding mode used in IEEE 754 computing functions and operators.

Answer 3

By taking a number's 2nd decimal place and seeing if it is .45 or higher.

Answer 4

The usual rule for school use is If it's 0.5 or higher, round to the next whole number up.

If it's 0.4999 or lower, round to the whole number part, i.e. round down.