The CAS Registry Mumber 161776-79-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,6,1,7,7 and 6 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 161776-79: (8*1)+(7*6)+(6*1)+(5*7)+(4*7)+(3*6)+(2*7)+(1*9)=160 160 % 10 = 0 So 161776-79-0 is a valid CAS Registry Number.