The CAS Registry Mumber 101924-18-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,0,1,9,2 and 4 respectively; the second part has 2 digits, 1 and 8 respectively. Calculate Digit Verification of CAS Registry Number 101924-18: (8*1)+(7*0)+(6*1)+(5*9)+(4*2)+(3*4)+(2*1)+(1*8)=89 89 % 10 = 9 So 101924-18-9 is a valid CAS Registry Number.