A dvanda compound denoting a fixed number (ekatva) of concrete things (adhikaraṇa) is not singular.,
As, दश दन्तोष्ठाः 'ten sets of teeth and lips'; दशमार्दङ्गिकपाणविकाः 'ten sets of drum and panavika players.' Compare 2.4.2.,
अधिकरन-एतावत्त्वे च
Adhyāya 2 · Pāda 4 · Rule 15