The CAS Registry Mumber 110354-15-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,0,3,5 and 4 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 110354-15: (8*1)+(7*1)+(6*0)+(5*3)+(4*5)+(3*4)+(2*1)+(1*5)=69 69 % 10 = 9 So 110354-15-9 is a valid CAS Registry Number.