# ROUNDDOWN

The `ROUNDDOWN` formula rounds a number down to a specified number of decimal places. It is commonly used in financial calculations, such as calculating the total cost of a purchase including tax. The formula takes a required `value` parameter and an optional `places` parameter specifying the number of decimal places to round to.

## Usage

Use the `ROUNDDOWN` formula with the syntax shown below, it has 1 required parameter and 1 optional parameter:

Parameters:
1. value (required):
The number to be rounded down.
2. places (optional):
The number of decimal places to round to. If omitted, the default value is 0.

## Examples

Here are a few example use cases that explain how to use the `ROUNDDOWN` formula in Google Sheets.

### Rounding down to the nearest whole number

When calculating the quantity of items needed for a project, you may want to round down to the nearest whole number to ensure that you don't overestimate the amount needed. The `ROUNDDOWN` formula can be used to achieve this.

### Calculating sales tax

When calculating sales tax on a purchase, you may want to round down the total cost to the nearest cent. The `ROUNDDOWN` formula can be used to achieve this.

### Calculating depreciation

When calculating depreciation of an asset, you may want to round down the calculated value to the nearest dollar. The `ROUNDDOWN` formula can be used to achieve this.

## Common Mistakes

`ROUNDDOWN` not working? Here are some common mistakes people make when using the `ROUNDDOWN` Google Sheets Formula:

### Missing value argument

If you forget to provide the value argument, the function will return an error. Make sure to include the value you want to round down.

### Incorrect number of arguments

If you provide more or less than two arguments, the function will return an error. Double-check that you have included both the value and the number of decimal places.

### Incorrect data type

If you provide a value that is not a number, the function will return an error. Make sure to only use numeric values as the first argument.

### Negative number of decimal places

If you provide a negative number of decimal places, the function will return an error. Make sure to only use positive values for the second argument.

### Incorrect rounding direction

Remember that ROUNDDOWN always rounds down, regardless of the value. If you need to round up, use the ROUNDUP function instead.

The following functions are similar to `ROUNDDOWN` or are often used with it in a formula:

• `ROUND`

The `ROUND` formula rounds a number to a specified number of decimal places. It is commonly used to simplify large numbers or to make a number more readable. The formula can round both positive and negative numbers. If the `places` parameter is not specified, the formula rounds to the nearest integer.

• `CEILING`

The `CEILING` function returns a number rounded up to the nearest multiple of a specified factor. It is commonly used to round up prices to the nearest dollar or to adjust numbers to fit into specific increments.

• `FLOOR`

The FLOOR formula rounds a given number down to the nearest multiple of a specified factor. It is commonly used when dealing with financial data or when working with time values. The function takes a value and an optional factor as arguments and returns the rounded down value.

• `MROUND`

The `MROUND` function rounds a number to the nearest multiple of a specified factor. It is commonly used when dealing with financial data, such as currency or interest rate calculations.

You can learn more about the `ROUNDDOWN` Google Sheets function on Google Support.