The CAS Registry Mumber 303962-64-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,0,3,9,6 and 2 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 303962-64: (8*3)+(7*0)+(6*3)+(5*9)+(4*6)+(3*2)+(2*6)+(1*4)=133 133 % 10 = 3 So 303962-64-3 is a valid CAS Registry Number.