The CAS Registry Mumber 83443-88-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,4,4 and 3 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 83443-88: (7*8)+(6*3)+(5*4)+(4*4)+(3*3)+(2*8)+(1*8)=143 143 % 10 = 3 So 83443-88-3 is a valid CAS Registry Number.