The CAS Registry Mumber 672-44-6 includes 6 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 3 digits, 6,7 and 2 respectively; the second part has 2 digits, 4 and 4 respectively. Calculate Digit Verification of CAS Registry Number 672-44: (5*6)+(4*7)+(3*2)+(2*4)+(1*4)=76 76 % 10 = 6 So 672-44-6 is a valid CAS Registry Number.