The CAS Registry Mumber 159406-74-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,9,4,0 and 6 respectively; the second part has 2 digits, 7 and 4 respectively. Calculate Digit Verification of CAS Registry Number 159406-74: (8*1)+(7*5)+(6*9)+(5*4)+(4*0)+(3*6)+(2*7)+(1*4)=153 153 % 10 = 3 So 159406-74-3 is a valid CAS Registry Number.