The CAS Registry Mumber 7630-02-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,6,3 and 0 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 7630-02: (6*7)+(5*6)+(4*3)+(3*0)+(2*0)+(1*2)=86 86 % 10 = 6 So 7630-02-6 is a valid CAS Registry Number.