The CAS Registry Mumber 196938-30-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,9,6,9,3 and 8 respectively; the second part has 2 digits, 3 and 0 respectively. Calculate Digit Verification of CAS Registry Number 196938-30: (8*1)+(7*9)+(6*6)+(5*9)+(4*3)+(3*8)+(2*3)+(1*0)=194 194 % 10 = 4 So 196938-30-4 is a valid CAS Registry Number.