The CAS Registry Mumber 4976-93-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,9,7 and 6 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 4976-93: (6*4)+(5*9)+(4*7)+(3*6)+(2*9)+(1*3)=136 136 % 10 = 6 So 4976-93-6 is a valid CAS Registry Number.