ROUND, ROUNDUP, ROUNDDOWN의 차이
INT(-2.1)을 ROUNDDOWN과 같다고 쓰고 보니 달랐다. 이 시트에서 ROUNDDOWN(-2.1,0)은 -2, INT(-2.1)은 -3, TRUNC(-2.1)은 -2, ROUND는 -2, ROUNDUP은 -3이다. ROUNDDOWN은 0 쪽이다. INT는 그 수 이하의 정수라서 음수에서는 0에서 더 멀어진다. Microsoft의 INT와 TRUNC 설명도 같다.
빠른 답변
INT(-2.1)을 ROUNDDOWN과 같다고 쓰고 보니 달랐다. 이 시트에서 ROUNDDOWN(-2.1,0)은 -2, INT(-2.1)은 -3, TRUNC(-2.1)은 -2, ROUND는 -2, ROUNDUP은 -3이다. ROUNDDOWN은 0 쪽이다. INT는 그 수 이하의 정수라서 음수에서는 0에서 더 멀어진다. Microsoft의 INT와 TRUNC 설명도 같다.
=ROUNDDOWN(-2.1,0) → -2
=INT(-2.1) → -3
=TRUNC(-2.1) → -2
=ROUND(-2.1,0) → -2
=ROUNDUP(-2.1,0) → -3확인 사항
ROUNDUP은 0에서 멀어지고, ROUNDDOWN은 0 쪽으로 간다. 양의 무한대나 음의 무한대 쪽이 아니다. -2.9에서 ROUNDUP은 -3, ROUNDDOWN은 -2다. 2.1에서 ROUNDUP은 3, ROUNDDOWN은 2다. 이 시트의 ROUND는 중간값을 0에서 멀어지게 하며, 은행가 반올림이 아니다. 2.5는 3, -2.5는 -3이고, 가까운 짝수가 되지 않았다. MROUND와 FLOOR.MATH는 시험하지 않았다.
주의점 및 호환성
두 번째 인수는 자릿수다. 양수는 소수 자리, 0은 정수, 음수는 소수점 왼쪽이다. 12.34를 -1 자리로 하면 ROUND는 10, ROUNDUP은 20, ROUNDDOWN은 10이다. 2.25를 소수 1자리로 하면 ROUND와 ROUNDUP은 2.3, ROUNDDOWN은 2.2다. 2.15는 이 시트에서 ROUND가 2.2였다. INT에는 자릿수 인수가 없고, 여기서 TRUNC는 기본값이라 12.34는 여전히 12다.
영어 상세 예제, 수식 및 작성자 메모
Excel ComparisonI used INT on -2.1 as if it were ROUNDDOWN. It is not.
=ROUNDDOWN(-2.1,0) → -2
=INT(-2.1) → -3
=TRUNC(-2.1) → -2
=ROUND(-2.1,0) → -2
=ROUNDUP(-2.1,0) → -3ROUNDDOWN moved toward zero. INT moved to the next integer below, which for a negative number is farther from zero. Microsoft’s INT page says that explicitly, and this Sheets file did the same thing: INT(-1.5) was -2, INT(-2.9) was -3. TRUNC just chopped the fraction, so it landed with ROUNDDOWN on every integer case I ran, including the negatives. Microsoft’s TRUNC page draws the same contrast with INT.
That “up” and “down” language is also the whole difference between ROUNDUP and ROUNDDOWN, and it is easy to read it as “toward plus infinity” and “toward minus infinity.” It is not. Microsoft’s ROUNDUP page says away from zero; ROUNDDOWN says toward zero. On -2.9, ROUNDUP went to -3 and ROUNDDOWN went to -2. On 2.1, ROUNDUP went to 3 and ROUNDDOWN stayed at 2.
ROUND is the ordinary half-away-from-zero function in this file, not a bankers’ tie-to-even:
=ROUND(2.5,0) → 3
=ROUND(1.5,0) → 2
=ROUND(0.5,0) → 1
=ROUND(-0.5,0) → -1
=ROUND(-1.5,0) → -2
=ROUND(-2.5,0) → -3If it had been banker’s rounding, 2.5 would have gone to 2 and -2.5 to -2. They did not. I did not test other halfway conventions, or MROUND, or FLOOR.MATH.
Digits, including to the left of the decimal
The second argument is the number of digits. Positive values are decimal places. Zero is an integer. A negative value moves left of the decimal point. 12.34 to -1 digit:
=ROUND(12.34,-1) → 10
=ROUNDUP(12.34,-1) → 20
=ROUNDDOWN(12.34,-1) → 10ROUNDUP jumps to 20 because that is the next multiple of ten away from zero. INT and TRUNC of 12.34 are still 12; they do not take a “tens” argument in the way I called them (INT has no digits argument, and I left TRUNC at the default).
One decimal place, for completeness:
=ROUND(2.25,1) → 2.3
=ROUNDUP(2.25,1) → 2.3
=ROUNDDOWN(2.25,1) → 2.2
=ROUND(2.15,1) → 2.2
=ROUNDUP(2.15,1) → 2.2
=ROUNDDOWN(2.15,1) → 2.12.15 rounded to 2.2 here. Binary floating-point can make .15 values misbehave in some workbooks; I am only reporting what this file returned, not a guarantee about every x.15.
The functions returned numbers, not text. I did not feed them text like "2.5", and I am not going to guess whether that would be coerced or come back #VALUE!. For actual #VALUE! and #NUM! cases in this workbook, see VALUE Error and NUM Error. Division that blows up is still a DIV/0 Error, and rounding will not save it.
If I need “always toward zero,” I use ROUNDDOWN or TRUNC. If I need “always away from zero,” ROUNDUP. If I need “the next integer down the number line, including through zero,” INT. ROUND is the everyday midpoint function, and in this file those midpoints went away from zero.