The CAS Registry Mumber 84775-51-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,7,7 and 5 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 84775-51: (7*8)+(6*4)+(5*7)+(4*7)+(3*5)+(2*5)+(1*1)=169 169 % 10 = 9 So 84775-51-9 is a valid CAS Registry Number.