The CAS Registry Mumber 65149-53-3 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 3 respectively. Calculate Digit Verification of CAS Registry Number 65149-53: (7*6)+(6*5)+(5*1)+(4*4)+(3*9)+(2*5)+(1*3)=133 133 % 10 = 3 So 65149-53-3 is a valid CAS Registry Number.