The CAS Registry Mumber 67192-21-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,7,1,9 and 2 respectively; the second part has 2 digits, 2 and 1 respectively. Calculate Digit Verification of CAS Registry Number 67192-21: (7*6)+(6*7)+(5*1)+(4*9)+(3*2)+(2*2)+(1*1)=136 136 % 10 = 6 So 67192-21-6 is a valid CAS Registry Number.