The CAS Registry Mumber 159434-79-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,9,4,3 and 4 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 159434-79: (8*1)+(7*5)+(6*9)+(5*4)+(4*3)+(3*4)+(2*7)+(1*9)=164 164 % 10 = 4 So 159434-79-4 is a valid CAS Registry Number.