The CAS Registry Mumber 4370-99-4 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,3,7 and 0 respectively; the second part has 2 digits, 9 and 9 respectively. Calculate Digit Verification of CAS Registry Number 4370-99: (6*4)+(5*3)+(4*7)+(3*0)+(2*9)+(1*9)=94 94 % 10 = 4 So 4370-99-4 is a valid CAS Registry Number.