The CAS Registry Mumber 11021-24-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,1,0,2 and 1 respectively; the second part has 2 digits, 2 and 4 respectively. Calculate Digit Verification of CAS Registry Number 11021-24: (7*1)+(6*1)+(5*0)+(4*2)+(3*1)+(2*2)+(1*4)=32 32 % 10 = 2 So 11021-24-2 is a valid CAS Registry Number.