Specific requests are both powerful yet insidious as deal tactics. They work because they are narrow and beg for a binary decision. Studies show that precise requests are more likely to gain acceptance simply because they are precise, not necessarily because of the substance[x]. Further studies show that pricing of all sorts is more persuasive when precise, rather than using round numbers.
An example is the pricing of a house. When detailed numbers are presented, it has the impression of precision, truth, or accuracy. A house priced at $300,000 is less likely to close than a house priced at $325,000.
To deal with this, do not focus too heavily on the numbers, but disaggregate and question the elements individually.