Change filename to numbers

Is it possible to change name of folder this way:

I have 100 folders with different names.
I want to call them just by numbers - 1, 2, 3, 4 and so on

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Reply to #1:
I think i found the answer myself.
It seams that i can use both first and second alternative.
Is there a difference between those ywo.
I have tried them and i get the same result.

I had one folder named A and one folder named B
I want to rename to 1 and 2. I tried both and get the same result.

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