The CAS Registry Mumber 80202-58-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,0,2,0 and 2 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 80202-58: (7*8)+(6*0)+(5*2)+(4*0)+(3*2)+(2*5)+(1*8)=90 90 % 10 = 0 So 80202-58-0 is a valid CAS Registry Number.