The CAS Registry Mumber 111190-23-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,1,1,9 and 0 respectively; the second part has 2 digits, 2 and 3 respectively. Calculate Digit Verification of CAS Registry Number 111190-23: (8*1)+(7*1)+(6*1)+(5*1)+(4*9)+(3*0)+(2*2)+(1*3)=69 69 % 10 = 9 So 111190-23-9 is a valid CAS Registry Number.