The CAS Registry Mumber 4493-40-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,4,9 and 3 respectively; the second part has 2 digits, 4 and 0 respectively. Calculate Digit Verification of CAS Registry Number 4493-40: (6*4)+(5*4)+(4*9)+(3*3)+(2*4)+(1*0)=97 97 % 10 = 7 So 4493-40-7 is a valid CAS Registry Number.