The CAS Registry Mumber 2818-52-2 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,8,1 and 8 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 2818-52: (6*2)+(5*8)+(4*1)+(3*8)+(2*5)+(1*2)=92 92 % 10 = 2 So 2818-52-2 is a valid CAS Registry Number.