What error is corrected by focusing on “qimata al-dinar”?

Kitab al-Iqrar: Connected Exceptions, Quantities, and Cross-Category Exceptions

• Remembering that the original total is 100 dirhams
• Treating one dinar as a numerical deduction of just one dirham
• Recognizing the need to establish the dinar’s value
• Recognizing that the exception relates to the original right