The CAS Registry Mumber 4435-97-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,4,3 and 5 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 4435-97: (6*4)+(5*4)+(4*3)+(3*5)+(2*9)+(1*7)=96 96 % 10 = 6 So 4435-97-6 is a valid CAS Registry Number.