The CAS Registry Mumber 63213-40-1 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 0 respectively. Calculate Digit Verification of CAS Registry Number 63213-40: (7*6)+(6*3)+(5*2)+(4*1)+(3*3)+(2*4)+(1*0)=91 91 % 10 = 1 So 63213-40-1 is a valid CAS Registry Number.