The CAS Registry Mumber 78114-51-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,8,1,1 and 4 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 78114-51: (7*7)+(6*8)+(5*1)+(4*1)+(3*4)+(2*5)+(1*1)=129 129 % 10 = 9 So 78114-51-9 is a valid CAS Registry Number.