One would expect for the verse to write the number from numerically larger to smaller denominations, as the Torah usually does. However, as the Talmud (Megillah 11a) relates, Achashverosh first conquered seven lands, then twenty more, and finally one hundred more, spreading out his kingdom until he was ruler of 127 provinces. Taking his cue from the earlier mentioned idea that Achashverosh was an unworthy upstart, Rabbi Dovid Feintein writes in Kol Dodi that we are influenced psychologically by the first number we see. This is why marketing executives write $9.99 as the price for an item rather than $10. The 9 that people see first makes 10 seem much larger. This verse, accordingly, is emphasizing again that Achashverosh is an upstart, worthy of only the first seven of his 127 states.