The CAS Registry Mumber 67665-60-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,7,6,6 and 5 respectively; the second part has 2 digits, 6 and 0 respectively. Calculate Digit Verification of CAS Registry Number 67665-60: (7*6)+(6*7)+(5*6)+(4*6)+(3*5)+(2*6)+(1*0)=165 165 % 10 = 5 So 67665-60-5 is a valid CAS Registry Number.