How to use the FLOOR.MATH function
What is the FLOOR.MATH function?
The FLOOR.MATH function rounds a number down to the nearest integer or to the nearest multiple of significance.
Table of Contents
1. Introduction
What is a multiple?
In mathematics a multiple is a number that can be divided evenly by another number with no remainder. For a number to be a multiple it must be divisible by x with 0 remainder.
For a number x, multiples of x are numbers like 2x, 3x, 4x and so on. For example, 20 is a multiple of 4 since 20/ 4 = 5 with no remainder.
How to round numbers?
Rounding is a method to simplify a number by reducing its digits while keeping its approximate value close to the original value.
There are a few common ways to round:
- Round to a set number of decimal places, rounding 2.13579 to 2 decimal places gives 2.14.
- Round up or down to the nearest integer, rounding up 2.3 gives 3. Rounding down 2.3 gives 2.
- Round to a set increment, rounding to the nearest 10 rounds 17 to 20.
- Round to significant figures, rounding 2.333 to 3 significant figures gives 2.33.
When rounding, look at the first digit after where you want to round. If it's 5 or more, round up. If less than 5, round down. Rounding makes numbers cleaner and easier to work with in many everyday situations, however, they may also cause rounding errors like rounded values can compound errors. Rounding measurements and constants may reduces precision. It is better to round numbers after performing calculations than before.
What is a decimal place?
A decimal place refers to each position held by a digit in a number. The first decimal place is the tenths place (1/10), the second is the hundreds place (1/100) and so on.
What is a comma?
Commas are frequently used in large numbers to help read and interpret the values easier. Commas separate thousands place values in large numbers. For example:
- 10,000 - ten thousand
- 100,000 - one hundred thousand
- 1,000,000 - one million
The comma creates groups of three digits, making it easier to count the zeroes and understand the scale.
In decimal numbers with both whole and fractional parts, commas separate the whole number groups of three digits. For example:
- 3,421.256
- 102,734,221.985
What is an integer?
An integer is a whole number that can be positive, negative, or zero, but not a fraction or decimal.
What other Excel functions round numbers?
| ROUND | Rounds a number to a specified number of digits |
| ROUNDUP | Rounds a number up, away from zero |
| ROUNDDOWN | Rounds a number down, towards zero |
| MROUND | Rounds a number to the nearest multiple of a specified value |
| CEILING | Rounds a number up to its nearest multiple. |
| ODD | Returns number rounded up to the nearest odd integer. |
| EVEN | Rounds a number up to the nearest even whole number. |
| FIXED | Rounds a number to the specified number of decimals, lets you ignore comma separators. |
| FLOOR.MATH | Rounds a number down to the nearest integer or to the nearest multiple of significance. |
| FLOOR.PRECISE | Rounds a number down to the nearest integer or to the nearest multiple of significance. |
2. Syntax
FLOOR.MATH(number, [significance], [mode])
| number | Required. The number to be rounded down. |
| [significance] | Optional. The multiple to which you want to round. |
| [mode] | Optional. The direction (toward or away from 0) to round negative numbers. |
3. Example 1
This example shows how to use the FLOOR.MATH function with different arguments. The image shows the number to round down to its nearest multiple of significance in column B, the significance argument in column C and the mode in column D. The result is shown in column F.
The first number in cell B3 is 34.721. The arguments are:
- number - B3 (a cell reference to the value we want to round)
- [significance] - C3 (a cell reference to the multiple of significance)
- mode: not specified (The direction toward or away from 0 to round negative numbers)
Formula in cell F3:
Cell F3 returns 34 based on 34.721 and 1 as the multiple of significance. 34 is the nearest multiple of significance if rounded down.
The second number is in cell B4 which is -15631.053. The arguments are:
- number - B4 (a cell reference to the value we want to round)
- [significance] - C4 (a cell reference to the multiple of significance)
- mode: not specified (The direction toward or away from 0 to round negative numbers)
Formula in cell F3:
Cell F3 returns -15632 based on input number -15631.053 and the multiple of significance is 2. -15632 is the nearest multiple of significance if rounded down.
The third number is in cell B5 which is also -15631.053. The arguments are:
- number - B5 (a cell reference to the value we want to round)
- [significance] - C5 (a cell reference to the multiple of significance)
- mode: -1 (The direction toward or away from 0 to round negative numbers)
Formula in cell F3:
Cell F3 returns -15630 based on input number -15631.053, the multiple of significance is 2, and the mode argument is -1 meaning it rounds up if the input value is a negative value. -15630 is the nearest multiple of significance if rounded up.
4. Example 2
A rectangular shape has an area equal to the square root of 92 square units. If the length of this rectangle is 4 units, what is its width? Round the number down to an multiple of significance of 0.2 using the MATH.FLOOR function.
Lets begin calculating the width of the rectangular shape. Area is the size of the surface enclosed by the rectangle expressed in square units like square meters, square feet, etc. Width is the measure of one of the shorter sides of the rectangle perpendicular to the length.
The units used for length and width must be the same and the area will be expressed in square units of those same units.
Area = length * width
Area = square root of 92
height = 4
width = area / length
width = √92 / 4
FLOOR.MATH arguments:
number = 92^0.5 / 4
significance = 0.2
Formula in cell C21:
√92 / 4 = 2.39791576165636 and the FLOOR.MATH function converts it to 2.2 units which represents the width of the rectangular shape.
Functions in 'Math and trigonometry' category
The FLOOR.MATH function function is one of 66 functions in the 'Math and trigonometry' category.
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