The CAS Registry Mumber 4421-46-9 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,4,2 and 1 respectively; the second part has 2 digits, 4 and 6 respectively. Calculate Digit Verification of CAS Registry Number 4421-46: (6*4)+(5*4)+(4*2)+(3*1)+(2*4)+(1*6)=69 69 % 10 = 9 So 4421-46-9 is a valid CAS Registry Number.