How to multiply in Python

Introduction

Multiplication is one of the basic arithmetic operations that we learn in our early school days, and it's a topic that's essential to understand no matter what programming language you're learning. In Python, there are several ways to multiply numbers or even other data types. In this blog post, we will explore various methods of multiplication in Python, starting with the basics and then moving on to more advanced techniques. We will also provide plenty of code examples along the way to help you get hands-on experience with these concepts.

Basic Multiplication

In Python, the most straightforward way to multiply two numbers is by using the `*` operator. This operator works with integers, floats, and even complex numbers. Here's a simple example:

``````a = 5
b = 3
result = a * b
print(result)  # Output: 15
``````

In this example, we define two variables, `a` and `b`, which store the numbers we want to multiply. We then use the `*` operator to multiply these numbers and store the result in another variable, `result`. Finally, we print the result to the console.

Let's take another example using floats:

``````a = 5.5
b = 3.2
result = a * b
print(result)  # Output: 17.6
``````

As you can see, the `*` operator works seamlessly with floating-point numbers as well.

Multiplying Lists and Strings

In Python, you can use the `*` operator to multiply not only numbers but also lists and strings. When you multiply a list or a string by an integer, Python repeats the content of that list or string the specified number of times. Let's take a look at how this works.

Multiplying Lists

``````my_list = [1, 2, 3]
result = my_list * 3
print(result)  # Output: [1, 2, 3, 1, 2, 3, 1, 2, 3]
``````

In this example, we define a list called `my_list` containing three integers. We then multiply this list by `3`, which repeats the list three times. The result is a new list with the original content repeated three times.

Multiplying Strings

``````my_string = "hello"
result = my_string * 3
print(result)  # Output: hellohellohello
``````

In this example, we define a string called `my_string` and multiply it by `3`, which repeats the string three times. The result is a new string with the original content repeated three times.

Multiplying Arrays and Matrices

In some cases, you may need to perform element-wise or matrix multiplication on arrays or matrices, which are common data structures in scientific computing, data science, and machine learning. Python's NumPy library is a powerful tool for working with arrays and matrices, and it provides built-in functions to perform various types of multiplication.

Element-wise Multiplication

Element-wise multiplication is the process of multiplying corresponding elements of two arrays or matrices. Here's an example using NumPy:

``````import numpy as np

array1 = np.array([1, 2, 3])
array2 = np.array([4, 5, 6])
result = np.multiply(array1, array2)
print(result)  # Output: [ 4 10 18]
``````

In this example, we first import the NumPy library and create two NumPy arrays, `array1` and `array2`. We then use the `np.multiply()` function to perform element-wise multiplication on these arrays, resulting in a new array with the product of the corresponding elements.

Matrix Multiplication

Matrix multiplication, also called dot product, is a more complex operation that involves multiplying two matrices according to specific rules. Here's an example using NumPy:

``````import numpy as np

matrix1 = np.array([[1, 2], [3, 4]])
matrix2 = np.array([[5, 6], [7, 8]])
result = np.dot(matrix1, matrix2)
print(result)
# Output:
# [[19 22]
#  [43 50]]
``````

In this example, we create two 2x2 matrices, `matrix1` and `matrix2`, and use the `np.dot()` function to perform matrix multiplication on them. The result is a new 2x2 matrix with the dot product of the input matrices.

Some Tips and Tricks

While the methods we've covered so far will be sufficient for most multiplication tasks in Python, here are a few additional tips and tricks that can come in handy:

Using the `**` Operator for Exponents

The `**` operator can be used to raise a number to a given power (exponentiation). For example, to calculate 2 raised to the power of 3, you can use the following code:

``````result = 2 ** 3
print(result)  # Output: 8
``````

Using the `pow()` Function for Exponentiation and Modular Exponentiation

The built-in `pow()` function can be used for exponentiation and modular exponentiation. For example, to calculate 2 raised to the power of 3, you can use the following code:

``````result = pow(2, 3)
print(result)  # Output: 8
``````

To perform modular exponentiation (i.e., finding the remainder of a number raised to a given power and then divided by a specified divisor), you can use the `pow()` function with a third argument. For example, to calculate `(2 ** 3) % 5`, you can use the following code:

``````result = pow(2, 3, 5)
print(result)  # Output: 3
``````

Conclusion

In this blog post, we've explored various ways to perform multiplication in Python, starting with basic multiplication using the `*` operator, and moving on to more advanced techniques such as multiplying lists, strings, arrays, and matrices. We also covered some useful tips and tricks for working with exponents and modular exponentiation. Now that you have a solid understanding of how to multiply in Python, you can apply these concepts to your own projects and continue to build your programming skills.

Learn to code in our 100% online programs

Altcademy coding bootcamp offers beginner-friendly, online programs designed by industry experts to help you become a coder. 85%+ of Altcademy alumni are hired within 6 months after graduation. See how we teach, or click on one of the following programs to find out more.