The CAS Registry Mumber 133447-44-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,3,4,4 and 7 respectively; the second part has 2 digits, 4 and 4 respectively. Calculate Digit Verification of CAS Registry Number 133447-44: (8*1)+(7*3)+(6*3)+(5*4)+(4*4)+(3*7)+(2*4)+(1*4)=116 116 % 10 = 6 So 133447-44-6 is a valid CAS Registry Number.