Randomly add and deduct a number for my website

I'm new to javascript/jquery and I can't seem to find any answers for a script that randomly changes the number I have on my website...

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So this is what I'm looking for: I've a number (lets say 200) and I want this number to increase and decrease randomly between 100 and 300 every second.

So it needs change the number it displays like this: 200 -> 230 -> 166-> 281 -> 105-> 195 and so on...

Obviously the numbers are just an example. Many thanks in advance if someone is able to help me out!