In this blog, we will write code to calculate 3×3 matrix multiplication. A matrix is a 2D array, which means it is a list inside a list. To multiply two matrices, their dimensions should be the same. For this tutorial, we require square matrices.

A matrix is known as a square matrix when its number of rows is equal to the number of columns. We will create two programs here, one in C++ and the other in the Python programming language.

Each of the programs will ask the user to enter the elements for two 3×3 matrices. Each matrix will have 9 elements. The program then multiplies the two matrices and prints the resultant matrix.

## How to Calculate 3×3 Matrix Multiplication?

### C++ Program to Calculate 3×3 Matrix Multiplication

#include<iostream.h> #include< conio.h> #include<stdio.h> #include<math.h> void main() { clrscr(); int arr1[3][3],arr2[3][3],arr3[3][3]; cout<<"Enter the Elements of Array 1: "<<endl; for(int i=0;i<3;i++) { for(int j=0;j<3;j++) cin>>arr1[i][j]; } cout<<"Enter the Elements of Array2:"<<endl; for(i=0;i<3;i++) {for(int j=0;j<3;j++) cin>>arr2[i][j]; } for(i=0;i<3;i++) { for(int j=0;j<3;j++) {arr3[i][j]=0; for(int k=0;k<3;k++) arr3[i][j]=arr3[i][j]+(arr1[i][k]*arr2[k][j]); cout<<arr3[i][j]<<" "; } cout<<endl; } getch(); }

**Output:**

Enter the Elements of Array 1: 2 4 5 6 3 2 4 7 3 Enter the Elements of Array 2: 1 3 4 6 8 6 4 2 6 46 48 62 32 46 54 58 74 76

### Python Program to Calculate 3×3 Matrix Multiplication

arr1=[[0,0,0],[0,0,0],[0,0,0]] arr2=[[0,0,0],[0,0,0],[0,0,0]] arr3= [[0,0,0],[0,0,0],[0,0,0]] print("Enter the Elements of Array 1:") for i in range(0,3): for j in range(0,3): element= int(input()) arr1[i][j]=element print("Enter the Elements of Array 2:") for i in range(3): for j in range(3): element2= int(input()) arr2[i][j]=element2 for i in range(3): for j in range(3): for k in range(3): arr3[i][j]+=arr1[i][k]*arr2[k][j] print(arr3[0],'\n',arr3[1],'\n',arr3[2])

**Output:**

Enter the Elements of Array 1: 3 4 5 2 54 6 23 45 12 Enter the Elements of Array 2: 23 34 54 5 76 65 34 76 85 [259, 786, 847] [520, 4628, 4128] [1162, 5114, 5187]

## Conclusion

Matrix multiplication is a common endeavor in scientific and mathematical programming. Hence, every programmer must be aware of it. In this tutorial, we have provided code that is capable of multiplying only a 3×3 matrix.

To learn the concept better, you can design the program for other square matrices, like 4×4 and 5×5 matrices. Moreover, you can create a program that can multiply square matrices of any size. However, doing so will require much knowledge and effort. Let us know if you are able to do so.

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