user11451: In After Effects I am trying my hands at this 

 and would like to add a random number between 45 and 55 in the upper right corner, which should change each second.

If I use Math.round(random(45,55)) I am getting pretty close, but the number updates maybe 20 times a second making it unusable. Is there a way to control how often a new number is generated? Is there another way to do this?
Just to clarify, I want sort of what is already in wiggle, where wiggle(1,30) wiggles once a second.

user1950: random updates at the sub-frame level (so its value actually changes even during a frame, for example when motion blur is on. You can see this as you zoom in on the graph editor of a property with a random value, it keeps changing as it zooms and the time is sub-sampled more).
To force it to update only once a second you need to use the seedRandom function, with the timeless attribute set to true, and a seed that changes every second. Using Math.floor(time) will return a value that increases once every second, on the second.
So something like:
seedRandom(Math.floor(time), timeless = true);
random(45,55);

will create a random value that stays constant for 1 second, and 
var holdTime = 5;
seedRandom(Math.floor(time/holdTime), timeless = true);
random(45,55);

will stay constant for 5 seconds - you can change the value of the variable holdTime to control how long the value holds for. For example to change once every frame, but not during sub-frame intervals set it to holdTime = thisComp.frameDuration;

11451: <p>In After Effects I am trying my hands at this <div class="youtube-embed"><div>
                <iframe width="640px" height="395px" src="https://www.youtube.com/embed/KLsk3lGbiVc?start=0"></iframe>
            </div></div> and would like to add a random number between 45 and 55 in the upper right corner, which should change each second.</p>

<p>If I use Math.round(random(45,55)) I am getting pretty close, but the number updates maybe 20 times a second making it unusable. Is there a way to control how often a new number is generated? Is there another way to do this?</p>

<p>Just to clarify, I want sort of what is already in wiggle, where wiggle(1,30) wiggles once a second.</p>
 1950: <p><code>random</code> updates at the sub-frame level (so its value actually changes even during a frame, for example when motion blur is on. You can see this as you zoom in on the graph editor of a property with a random value, it keeps changing as it zooms and the time is sub-sampled more).</p>

<p>To force it to update only once a second you need to use the <a href="http://adobe.ly/1DZW3md" rel="nofollow noreferrer"><code>seedRandom</code></a> function, with the <code>timeless</code> attribute set to <code>true</code>, and a <code>seed</code> that changes every second. Using <code>Math.floor(time)</code> will return a value that increases once every second, on the second.</p>

<p>So something like:</p>

<pre><code>seedRandom(Math.floor(time), timeless = true);
random(45,55);
</code></pre>

<p>will create a random value that stays constant for 1 second, and </p>

<pre><code>var holdTime = 5;
seedRandom(Math.floor(time/holdTime), timeless = true);
random(45,55);
</code></pre>

<p>will stay constant for 5 seconds - you can change the value of the variable <code>holdTime</code> to control how long the value holds for. For example to change once every frame, but not during sub-frame intervals set it to <code>holdTime = thisComp.frameDuration;</code></p>
