The CAS Registry Mumber 159339-70-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,9,3,3 and 9 respectively; the second part has 2 digits, 7 and 0 respectively. Calculate Digit Verification of CAS Registry Number 159339-70: (8*1)+(7*5)+(6*9)+(5*3)+(4*3)+(3*9)+(2*7)+(1*0)=165 165 % 10 = 5 So 159339-70-5 is a valid CAS Registry Number.