The CAS Registry Mumber 5696-69-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 5,6,9 and 6 respectively; the second part has 2 digits, 6 and 9 respectively. Calculate Digit Verification of CAS Registry Number 5696-69: (6*5)+(5*6)+(4*9)+(3*6)+(2*6)+(1*9)=135 135 % 10 = 5 So 5696-69-5 is a valid CAS Registry Number.