The CAS Registry Mumber 63213-35-4 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, 3 and 5 respectively. Calculate Digit Verification of CAS Registry Number 63213-35: (7*6)+(6*3)+(5*2)+(4*1)+(3*3)+(2*3)+(1*5)=94 94 % 10 = 4 So 63213-35-4 is a valid CAS Registry Number.