The CAS Registry Mumber 500535-02-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 5,0,0,5,3 and 5 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 500535-02: (8*5)+(7*0)+(6*0)+(5*5)+(4*3)+(3*5)+(2*0)+(1*2)=94 94 % 10 = 4 So 500535-02-4 is a valid CAS Registry Number.