The CAS Registry Mumber 137334-41-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,7,3,3 and 4 respectively; the second part has 2 digits, 4 and 1 respectively. Calculate Digit Verification of CAS Registry Number 137334-41: (8*1)+(7*3)+(6*7)+(5*3)+(4*3)+(3*4)+(2*4)+(1*1)=119 119 % 10 = 9 So 137334-41-9 is a valid CAS Registry Number.