Resolving 2+ actions at the same time.

In my little program I have some processes running parallel with each other. However there will be times where two processes finish what they're doing and then try to input their values into a 'queue' at the same time.

This queue is simply an alterable value. It works by taking whatever was already present, multiplies it by 10 and adds the newest value. So really it's just a big number.

Now when I have some processes finish at the same time one will get discarded and only one 'wins' out. Ideally I want both to somehow make it as that was the entire point of having a queue system.

I'm not sure if such a problem can be resolved but I'd like to hear thoughts.