The CAS Registry Mumber 113445-90-2 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, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 113445-90: (8*1)+(7*1)+(6*3)+(5*4)+(4*4)+(3*5)+(2*9)+(1*0)=102 102 % 10 = 2 So 113445-90-2 is a valid CAS Registry Number.