The CAS Registry Mumber 19097-34-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,9,0,9 and 7 respectively; the second part has 2 digits, 3 and 4 respectively. Calculate Digit Verification of CAS Registry Number 19097-34: (7*1)+(6*9)+(5*0)+(4*9)+(3*7)+(2*3)+(1*4)=128 128 % 10 = 8 So 19097-34-8 is a valid CAS Registry Number.