The CAS Registry Mumber 196805-72-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,9,6,8,0 and 5 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 196805-72: (8*1)+(7*9)+(6*6)+(5*8)+(4*0)+(3*5)+(2*7)+(1*2)=178 178 % 10 = 8 So 196805-72-8 is a valid CAS Registry Number.