The CAS Registry Mumber 110390-75-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,0,3,9 and 0 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 110390-75: (8*1)+(7*1)+(6*0)+(5*3)+(4*9)+(3*0)+(2*7)+(1*5)=85 85 % 10 = 5 So 110390-75-5 is a valid CAS Registry Number.