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```=L_SFROUND(value, sig_figs, [round_opt])
```
ArgumentDescriptionExample
valueThe value to round1234500
sig_figsNumber of significant figures4
round_opt0=ROUND (default), -1=ROUNDDOWN, 1=ROUNDUP0

## Description

L_SFROUND allows you to round a value to a specific number of significant figures, rather than specifying the decimal place like the ROUND function. This function does not determine how many significant figures a value has or what formatting is used to display a number. Instead, the user needs to specify the number of digits to use for rounding and modify number formatting as needed.

Rounding to a specific number of significant figures is a common need in scientific calculations. You might know that a resulting calculation should only have 3 significiant digits, but you might not know ahead of time whether it will be 0.534 or 53.4 or 534. The built-in ROUND function may not work for you in this situation, because it requires you to specify the decimal place.

See this article for an explanation of how the L_SFROUND function determines which digit to use for rounding.

The round_opt parameter can be used to specify whether the ROUND (default), ROUNDUP, or ROUNDDOWN functions are used.

If value=0, the function returns a value of 0.

The special "5" rules for significant figures are not included in this function. (eg. 2145 rounded to 3 significant figures becomes 2150).

Warning
This function does not control the displayed formatting of the number. For example, if you round the number 0.12345 to 3 significant digits, but you are still displaying 5 decimal places, the result will show 0.12300. Be careful not to confuse rounding with how values are displayed in Excel.

## Lambda Formula

This code for using L_SFROUND in Excel is provided under the License as part of the LAMBDA Library, but to use just this function, you may copy the following code directly into your spreadsheet.

### Code to Create Function via the Name Manager

```Name: L_SFROUND
Comment: Round a value to a number of significant figures
Refers To:

=LAMBDA(value,sig_figs,[round_opt],
LET(doc,"https://www.vertex42.com/lambda/sfround.html",
round_opt,IF(ISOMITTED(round_opt),0,round_opt),
exponent,INT(LOG10(ABS(value))),
roundto,sig_figs-(1+exponent),
IF(value=0,0,IF(sig_figs<1,"Error: sig_figs<1",
SWITCH(round_opt,
0,ROUND(value,roundto),
1,ROUNDUP(value,roundto),
-1,ROUNDDOWN(value,roundto),
)
))
))
```

### Code for AFE Workbook Module (Excel Labs Add-in)

```/**
* Round a value to a number of significant figures
* round_opt: 0=ROUND, -1=ROUNDDOWN, 1=ROUNDUP
* L_SFROUND(1234500,4,-1) = 1234000
*/
L_SFROUND = LAMBDA(value,sig_figs,[round_opt],
LET(doc,"https://www.vertex42.com/lambda/sfround.html",
round_opt,IF(ISOMITTED(round_opt),0,round_opt),
exponent,INT(LOG10(ABS(value))),
roundto,sig_figs-(1+exponent),
IF(value=0,0,IF(sig_figs<1,"Error: sig_figs<1",
SWITCH(round_opt,
0,ROUND(value,roundto),
1,ROUNDUP(value,roundto),
-1,ROUNDDOWN(value,roundto),
)
))
));
```

### Named Function for Google Sheets

```Name: L_SFROUND
Description: Round a value to a number of significant figures
Arguments: value, sig_figs, round_opt
Function:

LET(doc,"https://www.vertex42.com/lambda/sfround.html",
round_opt,IF(ISBLANK(round_opt),0,round_opt),
exponent,INT(LOG10(ABS(value))),
roundto,sig_figs-(1+exponent),
IF(value=0,0,IF(sig_figs<1,"Error: sig_figs<1",
SWITCH(round_opt,
0,ROUND(value,roundto),
1,ROUNDUP(value,roundto),
-1,ROUNDDOWN(value,roundto),
)
))
)
```
Warning
These functions are not compatible between Excel and Google Sheets. When using these functions, you will not be able to convert the Excel file to Google Sheets or vice versa without problems.

## L_SFROUND Examples

Example: Round a range of values to n significant digits
In Excel, the L_SFROUND function allows the value parameter to be an array or range of values.
```Test: Copy and Paste this LET function into a cell
=LET(
array, {0.123, 24.53, 0, 9876, -24.53},
sig_figs, 2,
round_opt, 0,
L_SFROUND(array,sig_figs,round_opt)
)

Result: {0.12, 25, 0, 9900, -25}
```

For Google Sheets, you can use the MAP function to apply L_SFROUND to an array of values, like this:

```=LET(
array, {0.123, 24.53, 0, 9876, -24.53},
sig_figs, 2,
round_opt, 0,
MAP(array,LAMBDA(cell,L_SFROUND(cell,sig_figs,round_opt)))
)

Result: {0.12, 25, 0, 9900, -25}
```
References & Resources