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It says “General” number format, not “Text”. And I got #VALUE! error when I try that formula

Can you give me an example of how a cell looks? In your first message you asked: How can I transform this text content into a number usable in formula?

I wanna now exactly what is on this cells. Thanks.

It's a selected cell, “General” number format.

SC-2017-06-04_151848.jpg

It is imported from here:

http://coinmarketcap.com/

If you have the cells already in General format, you can use them to create any formulas/calculations with them. For instance, this image shows a selection of cells that are on General format, as you can see at the bottom of the image, excel uses the selection to calculate sum and average.

Maybe I'm not understanding the question. I'm sorry.

It's simple. You try to import data from the coinmarketcap, and then try to use a cell with price data in a formula.