Figures in a deal relating to currency (7)

I believe the answer is:

decimal

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'figures in' is the definition.
The definition and answer can be both quantities as well as being singular nouns.
Maybe there's a link between them I don't understand?

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for decimal that I've seen before include "Relating to ten" , "Medical (anag.)" , "In base ten" , "of Number Ten" , "(System) based on tens" .)

I've seen this clue in the Evening Standard.

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