The CAS Registry Mumber 40017-79-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 4,0,0,1 and 7 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 40017-79: (7*4)+(6*0)+(5*0)+(4*1)+(3*7)+(2*7)+(1*9)=76 76 % 10 = 6 So 40017-79-6 is a valid CAS Registry Number.