The CAS Registry Mumber 2274-65-9 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 2,2,7 and 4 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 2274-65: (6*2)+(5*2)+(4*7)+(3*4)+(2*6)+(1*5)=79 79 % 10 = 9 So 2274-65-9 is a valid CAS Registry Number.