The CAS Registry Mumber 65149-51-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,5,1,4 and 9 respectively; the second part has 2 digits, 5 and 1 respectively. Calculate Digit Verification of CAS Registry Number 65149-51: (7*6)+(6*5)+(5*1)+(4*4)+(3*9)+(2*5)+(1*1)=131 131 % 10 = 1 So 65149-51-1 is a valid CAS Registry Number.