The CAS Registry Mumber 1020-32-2 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 1,0,2 and 0 respectively; the second part has 2 digits, 3 and 2 respectively. Calculate Digit Verification of CAS Registry Number 1020-32: (6*1)+(5*0)+(4*2)+(3*0)+(2*3)+(1*2)=22 22 % 10 = 2 So 1020-32-2 is a valid CAS Registry Number.