Sanskrit form a.s.tau

From: deshpandem
Message: 17245
Date: 2002-12-22

Hello friends,

In Sanskrit, the nominative form for "eight" comes out to be
a.s.tau (a dual-like appearance), while forms for instrumental
etc. come out looking like a.s.taabhi.h (with regular plural
endings). Is there an IE based explanation for this behavior?

Madhav Deshpande