ROUNDDOWN always rounds a number toward zero, regardless of the digit that follows — the mirror image of ROUNDUP.
ROUNDDOWN rounds a number toward zero to a specified number of digits, no matter what the next digit is — 4.9 rounds down to 4 just as readily as 4.1 does.
Use it whenever overestimating would cause a problem — like calculating how many complete teams of 4 can be formed from 17 people (4 full teams, not 4.25).
=ROUNDDOWN(number, num_digits)| Argument | Description |
|---|---|
| number required | The value to round. |
| num_digits required | How many digits to round to. 0 rounds to a whole number, negative values round to tens/hundreds. |
=ROUNDDOWN(4.567,2)Returns 4.56 — truncates rather than rounds to nearest.
=ROUNDDOWN(12.9,0)Returns 12 — any fractional amount is simply dropped.
=ROUNDDOWN(129,-1)Returns 120.
=ROUNDDOWN(17/4,0)17 people split into teams of 4 makes 4 complete teams, with 1 person left over — ROUNDDOWN avoids implying a partial 5th team.
If rounding up would overstate capacity or availability, ROUNDDOWN is the honest choice.
For negative numbers, ROUNDDOWN moves toward 0, not further away — -4.9 rounds to -4, not -5.
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