The CAS Registry Mumber 89999-52-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,9,9,9 and 9 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 89999-52: (7*8)+(6*9)+(5*9)+(4*9)+(3*9)+(2*5)+(1*2)=230 230 % 10 = 0 So 89999-52-0 is a valid CAS Registry Number.