The affix ac comes after a tat-puruṣa samāsa ending in the word aṅguli when a numeral or an indeclinable precedes it.,
Thus द्वे अंगुलो प्रमाणमस्य = द्व्यंगुलम्, त्र्यंगुलम् ॥ This compounding takes place by 2.1.51. This is a Tadhitartha compound, the taddhita affix मात्रच् being elided by the Vartika प्रमाणे लो द्विगोर्नित्यम् \there is always the elision of the affix मात्रच् denoting measure when a Dvigu compound is formed\. See 5.2.37 Vart.)). So also when an Indeclinable precedes it: as निर्गामंगुलिभ्यो = निरंगुलम्, अत्यंगुलिः पुरुषः ॥ Why do we say when a Tatpurusha compound? Observe पंचांगुलिः, अत्यंगुलिः पुरुषः ॥ The word \Tatpurusha\ is understood in all the subsequent sutras up to 5.4.106.,