The CAS Registry Mumber 224443-82-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,2,4,4,4 and 3 respectively; the second part has 2 digits, 8 and 2 respectively. Calculate Digit Verification of CAS Registry Number 224443-82: (8*2)+(7*2)+(6*4)+(5*4)+(4*4)+(3*3)+(2*8)+(1*2)=117 117 % 10 = 7 So 224443-82-7 is a valid CAS Registry Number.