why isn't there data-type for variable like sort?

I have asked translations exponent number value like "4.8803077704e+06" into decimal one within XSLT.
At first, I tried number format="something" but failed. I think number element is not the way for this task.

I struggle to remember how I did handle the numbers on other languages. and found that I need a type cast.
that's because XML handle all data only as string, not other one.

Is this right? IMHO variable have to support data-type attribute. but I can't feel sure for my say. I'm newbie to XSL world.

well, Is there any way to translate 4.8803077704e+06 into decimal one?

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