How to use the Excel TRUNC function

Summary

The Excel TRUNC function returns a truncated number based on an (optional) number of digits. For example, TRUNC(4.9) will return 4, and TRUNC(-3.5) will return -3. The TRUNC function does no rounding, it simply truncates as specified.

Purpose

Truncate a number to a given precision

Return value

A truncated number

Syntax

=TRUNC (number, [num_digits])

Arguments

number - The number to truncate.
num_digits - [optional] The precision of the truncation (default is 0).

Usage notes

Use the TRUNC function to remove the fractional part of a number and return just the integer. For example, TRUNC(4.9) will return 4, and TRUNC(-3.5) will return -3. TRUNC does not do any rounding, it simply returns the integer part of the number.

TRUNC can also be used to return a set number of decimal places without rounding, using the num_digits argument. For example, TRUNC (PI(), 2) will return 3.14 and TRUNC (PI(), 3) will return 3.141.

Note:TRUNC and INT are similar functions because they both can return the integer part of a number. However, TRUNC simply truncates a number, while INT actually rounds a number down to an integer. With positive numbers, and when TRUNC is using the default of 0 for num_digits, both functions return the same results. With negative numbers, the results can be different. INT(-3.1) returns -4, because INT rounds down to the lower integer. TRUNC(-3.1) returns -3.

If you simply want the integer part of a number, you should use TRUNC.

Related functions

Excel INT Function

The Excel INT function returns the integer part of a decimal number by rounding down to the integer. Note the INT function rounds down, so negative numbers become more negative. For example, while INT(10.8) returns 10, INT(-10.8) returns -11.

Excel TRUNC Function

The Excel TRUNC function returns a truncated number based on an (optional) number of digits. For example, TRUNC(4.9) will return 4, and TRUNC(-3.5) will return -3. The TRUNC function does no rounding, it simply truncates as specified.

Excel ROUND Function

The Excel ROUND function returns a number rounded to a given number of digits. The ROUND function can round to the right or left of the decimal point.

Excel ROUNDDOWN Function

The Excel ROUNDDOWN function returns a number rounded down to a given number of decimal places. Unlike standard rounding, where only numbers less than 5 are rounded down, ROUNDDOWN rounds all numbers 1-9 down.

Excel ROUNDUP Function

The Excel ROUNDUP function returns a number rounded up to a given number of decimal places. Unlike standard rounding, where numbers less than 5 are rounded down, ROUNDUP always rounds numbers 1-9 up.

Excel MROUND Function

The Excel MROUND function returns a number rounded to a given multiple. MROUND will round a number up or down, depending on the nearest multiple.

Excel CEILING Function

The Excel CEILING function returns a given number rounded up to a specified multiple. For example, =CEILING(A1,5) could be used to round a price in A1 to the nearest 5 dollars. CEILING always rounds up.

Excel FLOOR Function

The Excel FLOOR function rounds a given number down to the nearest specified multiple. FLOOR works like the MROUND function, but FLOOR always rounds down.

Excel ODD Function

The Excel ODD function returns the next odd integer after rounding a given number up. The ODD function always rounds numbers up (away from zero) so positive numbers become larger and negative numbers become smaller (i.e. more negative).

Excel EVEN Function

The Excel EVEN function returns the next even integer after rounding a given number up. The EVEN function always rounds numbers up (away from zero) so positive numbers become larger and negative numbers become smaller (i.e. more negative).

Good links

Microsoft TRUNC function documentation

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