The CAS Registry Mumber 65149-56-6 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 6 respectively. Calculate Digit Verification of CAS Registry Number 65149-56: (7*6)+(6*5)+(5*1)+(4*4)+(3*9)+(2*5)+(1*6)=136 136 % 10 = 6 So 65149-56-6 is a valid CAS Registry Number.