समः सुटि

रु is substituted for the म् of स्म् (and thereby अँ or अं is substituted for अ) when the augment स् follows in a संहिता ।
The augment सुट् is added by 6.1.137 &c. Thus सँस्स्कर्त्ता or संस्स्कर्त्ता, सँस्स्कर्तुम् or संस्स्कर्तुम्, सँस्स्कर्त्तव्यम् or संस्स्कर्त्तव्यम् ॥ The word is thus evolved: सम् + स् + कर्ता = सर् + स् + कर्ता 8.3.5. Here rule 8.3.15 appears and requires to be changed to visarjaniya. This visarga may optionally be retained unchanged by 8.3.36. This, however, is not done in the present instance : but the visarga is always and necessarily changed to स् by 8.3.34. In fact, the option of 8.3.36 is a determinate option (vyavasthita vibhasha) and does not apply to the present case.

Or even this sutra may be so read as to teach the स् substitution as well. Thus, the sutra is समः स्सुटि with two स्, and the sutra will mean, "रु is substituted for the म् of सम् before सुट्, and this रु is always changed to स्" ॥

Why do we say "for the म् of सम्"? Observe उपस्कर्त्ता ॥ Why do we say "before सुट्"? Observe संकृति ॥

Vart:- For the finals of सम्, पुम् and कान् there is always substituted स ॥ There would arise anomalies, if रु be substituted. Thus संस्कर्त्ता, पुंस्स्कामा, कांस्स्कान् ॥ In fact, according to this vartika, रु is never substituted for सम् 8.3.5, पुम् 8.3.6 and कान् 8.3.12.

Vart:- समो वा लोपमेके ॥ Some would have the elision of the स् after सम् ॥ This Vartika is not given in the Kasika, but the Padamanjari gives it, and so also the Mahabhashya.

According to Bhattoji Dikshita there will be 108 forms of this word संस्कर्त्ता ॥ Thus सँस्कर्त्ता and संस्कर्त्ता with the elision of स् ॥ Then with two स्, as सँस्स्कर्त्ता or संस्स्कर्ता ॥ Then we apply 8.4.47 to this latter, and have three स, as सँस्स्स्कर्ता or संस्स्स्कर्ता ॥ The anusvara is considered to be a vowel (अच्) for this purpose. From the three nasal forms सँस्कर्ता, सँस्स्कर्ता and सँस्स्स्कर्ता, we get three more by doubling the क् by the vartika : शरः खयः ॥ The three forms having anusvara, will also double their anusvara in addition to क् doubling. Thus we have 12 forms in anusvara: and six in nasal, altogether 18 forms. Then the त will be doubled and trebled : and thus with one त, two त and three त, we have 3 x 18 = 54 forms. This will be doubled (2 x 54 = 108) when अण् is nasalised.