You're typing on your laptop and, suddenly, some of the keys start registering as numbers and symbols instead of letters. What's going on? Most likely, the answer lies with your Num Lock key. Here's why---and how to fix it.

What is Num Lock?

Num Lock, short for "number lock," is a feature of PC keyboards dating back to the very first IBM PC in 1981. To save room on the keyboard, IBM decided to make keys on the numeric keypad do double duty as both number keys and cursor keys. To switch modes between them, IBM introduced the Num Lock key.

Here is an example of a typical numeric keypad location on a desktop keyboard.

With Num Lock turned on, the numeric keypad on a desktop PC works like an adding machine keypad with numbers and symbols (such as *, /, and +) that represent mathematical operations. With Num Lock turned off, the keypad registers as cursor keys (like up and down arrow) and some editing keys (such as Home and Insert).

What's Different About Num Lock on a Laptop?

Most laptops don't have dedicated numeric keypads, so Num Lock works differently on them. Instead of changing cursor keys into numbers, it converts a section of the QWERTY letters on the keyboard into a virtual numeric keypad.

Here is an example a keyboard made by Acer for a Windows 10 laptop. When you press the Num Lock key (seen here highlit in a red rectangle), 15 of the keys switch modes into a simulated numeric keypad. When you push them, they register as the symbol highlit in the red circle.

Your laptop will most likely look different than this, but many manufacturers use some variation of using keys on the right side of the keyboard as a numeric keypad with Num Lock.

As a result, if you hit the Num Lock key by accident on a laptop, you might have a problem that looks like this.

In this case, you're typing numbers instead of letters because the Num Lock key is turned on. Here's how to turn it off.

How to Turn Off Num Lock on a Laptop

The first step to turning off Num Lock is to find the Num Lock key on your laptop's keyboard. Its location can vary wildly by laptop manufacturer, but it is usually located in the upper-right corner of the keyboard.

Look for a small key that says some variation of "Num Lock," "NumLk," or even a small lock symbol with a number 1 inside.

For example, here is the Num Lock key's location on an Acer laptop.

In this case, the Num Lock key doubles as the F12 key, and it defaults to being Num Lock.

Some laptops may require you to hold down a Function key (commonly labeled "Fn") while pushing Num Lock to toggle it on or off.

Also, some laptop keyboards may have an indicator light showing whether Num Lock is turned on or off. For example, this YouTube video shows the location of the Num Lock key and its indicator light on a Sony VAIO notebook keyboard.

Your laptop will vary. If you have trouble locating your Num Lock key, try searching for a combination of your manufacturer name + "laptop" + "numlock key location" on Google, and you might find a websites with instructions specific to your laptop. For example, Google "lenovo laptop numlock key location," and you will find information about the Num Lock key on various ThinkPad laptops.

Preventing Future Num Lock Accidents

Now that you know about the Num Lock key, you can easily turn it off if you ever accidentally find yourself typing numbers again. If you'd like to receive an audible alert when you push the Num Lock key, follow this guide to make your computer play a sound when you type the Num Lock key, so you'll know if you pressed it by accident. There's also a way to see a notification in your Task Bar if you turn on Num Lock.

Good luck, and happy typing!