Following is a short tutorial how to get your Adsense code set up to work as a shortcode.
This is very effective if you want to place advertisements within a post or page.

So firstly log into your WordPress dashboard and browse over to Appearance > Editor.
Open up functions.php and scroll to the bottom.

Before the closing ?> paste the code below.

Save the file, head over to your post or page of choice and simply write [my_ads] to place an ad.

It will end up looking like this: