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Excel FLOOR.MATH Function

Excel FLOOR.MATH function
Summary 

The Excel FLOOR.MATH function rounds a number down to a specified multiple. Unlike the FLOOR function, FLOOR.MATH defaults to a multiple of 1, and provides explicit support for rounding negative numbers.

Purpose 
Round number down to nearest multiple
Return value 
A rounded number
Syntax 
=FLOOR.MATH (number, [significance], [mode])
Arguments 
  • number - The number that should be rounded.
  • significance - [optional] Multiple to use when rounding. Default is 1.
  • mode - [optional] For rounding negative numbers toward or away from zero. Default is 0.
Version 
Usage notes 

The Excel FLOOR.MATH function rounds a number down to a given multiple, where multiple is provided as the significance argument. If the number is already an exact multiple, no rounding occurs and the original number is returned.

The FLOOR.MATH function takes three arguments, numbersignificance, and mode. Number is the numeric value to round down, and is the only required argument. With no other input, FLOOR.MATH will round number down to the next integer.

The significance argument is the multiple to which number should be rounded. In most cases, significance is provided as a numeric value, but FLOOR.MATH can also understand time entered as text like "0:15". The default value of significance is 1.

The mode argument controls the direction negative values are rounded. By default, FLOOR.MATH rounds negative values away from zero. Setting mode to 1 or TRUE changes behavior so that negative values are rounded toward zero. The default value of mode is 0 or FALSE, so you can think of mode as a setting that means "round toward zero". Mode has no effect when number is positive.

Examples

By default, FLOOR.MATH rounds to the nearest integer, using a significance of 1.

=FLOOR.MATH(5.75) // returns 5
=FLOOR.MATH(2.55) // returns 2

Provide a value for significance to round to a different multiple:

=FLOOR.MATH(5.75,1) // returns 5
=FLOOR.MATH(5.75,3) // returns 3
=FLOOR.MATH(5.75,0.5) // returns 5.5

Rounding negative numbers

Positive numbers with decimal values are rounded down to the nearest integer, and negative numbers with decimal values are rounded away from zero:

=FLOOR.MATH(6.7) // returns 6
=FLOOR.MATH(-6.7) // returns -7

Control for rounding negative numbers toward zero or away from zero is provided with the (optional) mode argument. Mode defaults to zero or FALSE. When mode is omitted, FLOOR.MATH rounds negative numbers away from zero. When mode is set to TRUE, FLOOR.MATH rounds negative numbers toward zero. Mode has no effect on positive numbers.

=FLOOR.MATH(-4.1) // returns -5
=FLOOR.MATH(-4.1,1) // returns -5
=FLOOR.MATH(-4.1,1,TRUE) // returns -4

FLOOR.MATH vs FLOOR

The FLOOR.MATH function differs from the FLOOR function in these ways:

  1. Rounds down to the next integer by default (i.e. significance defaults to 1)
  2. Provides explicit control for rounding negative numbers (toward zero, away from zero)
  3. Changing the sign of significance has no effect on the result; use mode instead.

Notes

  • To round to the nearest multiple (up or down) see the MROUND function.
  • FLOOR.MATH works like FLOOR, but provides control for rounding negative values. 
  • The mode argument has no effect on positive numbers.
  • If number is an exact multiple of significance, no rounding occurs.

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