The CAS Registry Mumber 136819-59-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,6,8,1 and 9 respectively; the second part has 2 digits, 5 and 9 respectively. Calculate Digit Verification of CAS Registry Number 136819-59: (8*1)+(7*3)+(6*6)+(5*8)+(4*1)+(3*9)+(2*5)+(1*9)=155 155 % 10 = 5 So 136819-59-5 is a valid CAS Registry Number.