The **MMULT** function stands for “Matrix Multiplication”. It is a math and trigonometry function available in Microsoft Excel. The **MMULT** function multiplies two arrays and returns another matrix array. Here’s an overview of its basic use.

## MMULT Function in Excel: Syntax

**Function Objective:**

**The MMULT function multiplies two arrays of numbers and returns another array of numbers.**

**Syntax:**

*MMULT(array1, array2)*

**Arguments Explanation:**

Argument | Required/Optional | Explanation |
---|---|---|

array1 |
Required | The first array that you want to multiply. |

array2 |
Required | The second array that you want to multiply. |

**Return Parameter:**

**A matrix of number arrays.**

## Basics of Matrix Multiplication

We have two matrices, A and B., where A is an m by n matrix and B is an n by p matrix.

The product of these two matrices, C = AB; can be written as

The product of A and B that is C can also be written as,

## Example 1 – Inserting Number Arrays Manually in the MMULT Function in Excel

- Select the number of cells necessary to get all the cells of the matrix.
- Insert the formula with the
**MMULT**function. For this example, the formula is:

`=MMULT({1,2,3;4,5,6},{2,5;4,2;6,9})`

The starting matrices are 2×3 and 3×2, so the result is a 2×2 matrix, which is why we selected a 2×2 array.

- Press
**Ctrl + Shift + Enter**to execute the formula.

- You will see the curly brackets wrapped up in the formula. This is because the formula is in the form of a legacy array formula.

** Note**

If you are using Microsoft Office 365, you don’t need to select the range of cells or use **CTRL + SHIFT + ENTER** because Office 365 supports dynamic array formulas. Use the **ENTER** button only and the formula will auto-spill to the required number of cells unless it encounters a filled value or a merge.

## Example 2 – Using the MMULT Function in Excel to Multiply Two 3×3 Matrices

- Select a range of cells having a measurement of 3×3, as the output matrix dimension will be 3×3.
- Insert the following formula onto the top-left corner of the selection area. Cell
**B10**for this instance.

`=MMULT(B5:D7,F5:H7)`

The **B5:D7** is the range of the first array and **F5:H7** is the range of the second array.

- Press the
**Ctrl + Shift + Enter**buttons to execute the formula, unless you’re using Excel 365, in which case you can use Enter.

## Example 3 – Calculating the Product of a 2×3 Matrix with a 3×2 Matrix with the MMULT Function

- Select a 2-by-2 array of cells.
- Insert the following legacy array formula to the top-left corner of the selected cells.

`=MMULT(B5:D6,F5:G7)`

- Hit the
**Ctrl + Shift + Enter**buttons to execute the formula.

To do the same task in Excel **Office 365**, just insert the formula in any cell and press the **ENTER** button.

## Example 4 – Multiplying a 3×2 Matrix with a 2×3 Matrix Using Excel MMULT Function

- Select an area of 3×3.
- Input the following formula in the first cell of the selection area. Cell
**B10**for this instance.

`=MMULT(B5:C7,E5:G6)`

- Hit the
**Ctrl + Shift + Enter**buttons, or**Enter**if you’re using Excel 365.

## Example 5 – Using the MMULT Function to Multiply a 3×1 Matrix with a 1×3 Matrix

- Select 9 consecutive cells in a 3-by-3 array.
- Enter the following formula to the top-left corner of the selection area.

`=MMULT(B5:B7,E5:G5)`

- Apply with either
**Ctrl + Shift + Enter**or**Enter**depending on your program version.

## Example 6 – Combining SUM, MMULT, TRANSPOSE, and COLUMN Functions to Count the Rows with a Specific Value

We will count the total number of rows that contain the number 5. However, the number 5 can be present in more than one column of the row.

- Insert the following formula in cell
**D16**.

`=SUM(--(MMULT(--(B5:D14=5), TRANSPOSE(COLUMN(B5:D14)))>0))`

- Apply with either
**Ctrl + Shift + Enter**or**Enter**depending on your program version (older versions or Excel 365).

The formula uses matrix multiplication and converting all cell values to TRUE/FALSE (which are then converted to 1/0 via the double unary minus) depending on whether they are equal to 5 and if they are a number. The SUM function then sums all values of the array or matrix.

## Things to Remember

- The number of columns in array1 must be the same as the number of rows in array2. You’ll get a VALUE error otherwise.
- If the cells are blank or contain any text, the
**MMULT**function returns a**#VALUE**error. You can use matrix operations to convert values beforehand.

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What is the feature in MMULT? What does it represent?

Thanks

Hello

Roland Sprague,The MMULT functionof Excel represents the matrix multiplication we perform in mathematics. We can use this function if there happens to be two ranges in a sheet representing two matrices and we want to multiply them.You can find out more about matrix multiplication in

this sectionof the article. It is helpful for computing in linear algebra, transformation of coordinate systems, population modeling, etc.Regards

NiloyExcelDemy