The CAS Registry Mumber 941-39-9 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 9,4 and 1 respectively; the second part has 2 digits, 3 and 9 respectively. Calculate Digit Verification of CAS Registry Number 941-39: (5*9)+(4*4)+(3*1)+(2*3)+(1*9)=79 79 % 10 = 9 So 941-39-9 is a valid CAS Registry Number.