The CAS Registry Mumber 1008997-34-9 includes 10 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 7 digits, 1,0,0,8,9,9 and 7 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 1008997-34: (9*1)+(8*0)+(7*0)+(6*8)+(5*9)+(4*9)+(3*7)+(2*3)+(1*4)=169 169 % 10 = 9 So 1008997-34-9 is a valid CAS Registry Number.