The CAS Registry Mumber 59105-97-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 5,9,1,0 and 5 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 59105-97: (7*5)+(6*9)+(5*1)+(4*0)+(3*5)+(2*9)+(1*7)=134 134 % 10 = 4 So 59105-97-4 is a valid CAS Registry Number.