The CAS Registry Mumber 224950-42-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,2,4,9,5 and 0 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 224950-42: (8*2)+(7*2)+(6*4)+(5*9)+(4*5)+(3*0)+(2*4)+(1*2)=129 129 % 10 = 9 So 224950-42-9 is a valid CAS Registry Number.