The CAS Registry Mumber 85202-97-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,5,2,0 and 2 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 85202-97: (7*8)+(6*5)+(5*2)+(4*0)+(3*2)+(2*9)+(1*7)=127 127 % 10 = 7 So 85202-97-7 is a valid CAS Registry Number.