The CAS Registry Mumber 353255-88-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,5,3,2,5 and 5 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 353255-88: (8*3)+(7*5)+(6*3)+(5*2)+(4*5)+(3*5)+(2*8)+(1*8)=146 146 % 10 = 6 So 353255-88-6 is a valid CAS Registry Number.