The CAS Registry Mumber 65602-06-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,5,6,0 and 2 respectively; the second part has 2 digits, 0 and 6 respectively. Calculate Digit Verification of CAS Registry Number 65602-06: (7*6)+(6*5)+(5*6)+(4*0)+(3*2)+(2*0)+(1*6)=114 114 % 10 = 4 So 65602-06-4 is a valid CAS Registry Number.