The CAS Registry Mumber 26369-65-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,6,3,6 and 9 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 26369-65: (7*2)+(6*6)+(5*3)+(4*6)+(3*9)+(2*6)+(1*5)=133 133 % 10 = 3 So 26369-65-3 is a valid CAS Registry Number.