The CAS Registry Mumber 88741-55-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,8,7,4 and 1 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 88741-55: (7*8)+(6*8)+(5*7)+(4*4)+(3*1)+(2*5)+(1*5)=173 173 % 10 = 3 So 88741-55-3 is a valid CAS Registry Number.