The CAS Registry Mumber 74602-63-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,6,0 and 2 respectively; the second part has 2 digits, 6 and 3 respectively. Calculate Digit Verification of CAS Registry Number 74602-63: (7*7)+(6*4)+(5*6)+(4*0)+(3*2)+(2*6)+(1*3)=124 124 % 10 = 4 So 74602-63-4 is a valid CAS Registry Number.