This is a fun one, and it's not exactly easy, but it's doable. What we are going to do is add 0 to all of them, and we will do it at the same time. This is easier done in a macro, but if you don't know Excel VBA, we can do it here.
We are trying to get from this:

To this:

You can convert an entire range to number by adding 0 or multiplying 1 to the entire range. So, the flow will need to do the following steps:
Write "1" to a cell that you know will never be used; in the flow below, I chose Z1. Copy that, select your range, right click, Paste Special. In the Paste Special dialogue box, select "Multiply" and click OK. This will multiply all the numbers by 1; therefore making them numbers. Any blanks will show up as "0", so if you want to do away with that, that's a separate conversation.
Here is what the flow looks like:

I suggest using your own desktop recorder for those last 5 steps (the UIs). These UI clicks are a little slow (3-5 seconds each). If you would like it to go faster, you could navigate excel through send keys.
Best of luck!