The CAS Registry Mumber 63213-43-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,3,2,1 and 3 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 63213-43: (7*6)+(6*3)+(5*2)+(4*1)+(3*3)+(2*4)+(1*3)=94 94 % 10 = 4 So 63213-43-4 is a valid CAS Registry Number.