The CAS Registry Mumber 81246-72-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,1,2,4 and 6 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 81246-72: (7*8)+(6*1)+(5*2)+(4*4)+(3*6)+(2*7)+(1*2)=122 122 % 10 = 2 So 81246-72-2 is a valid CAS Registry Number.