The CAS Registry Mumber 3113-59-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 3,1,1 and 3 respectively; the second part has 2 digits, 5 and 9 respectively. Calculate Digit Verification of CAS Registry Number 3113-59: (6*3)+(5*1)+(4*1)+(3*3)+(2*5)+(1*9)=55 55 % 10 = 5 So 3113-59-5 is a valid CAS Registry Number.