The CAS Registry Mumber 113445-88-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,3,4,4 and 5 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 113445-88: (8*1)+(7*1)+(6*3)+(5*4)+(4*4)+(3*5)+(2*8)+(1*8)=108 108 % 10 = 8 So 113445-88-8 is a valid CAS Registry Number.