Matthew specifies that Judas was paid thirty pieces of silver to hand Jesus over. The coins are not merely a generic reference to money; the specified amount becomes part of Matthew's narrative and later reappears when Judas returns the payment.
The amount also participates in Matthew's scriptural framing of the betrayal.
The expression "pieces of silver" does not name the coin type in the verse itself, so attempts to calculate an exact modern dollar value can create false precision. The narrative importance lies in the fixed payment and in its biblical associations.
Matthew later connects the returned silver with the purchase of the potter's field and with prophetic Scripture. Thirty shekels also appears in Exodus 21:32 as compensation in a case involving a slave, while Zechariah 11:12-13 prominently features thirty pieces of silver and the potter/treasury imagery echoed in Matthew.
The background keeps the reader from treating the number as an incidental transaction detail. Matthew has made the amount memorable and then woven it into the aftermath of the betrayal.
At the same time, the passage should not be reduced to a simplistic modern price conversion. Its force is literary, scriptural, and moral: Jesus is handed over for a specified payment whose imagery reverberates through Israel's Scriptures.