The CAS Registry Mumber 86869-56-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,6,8,6 and 9 respectively; the second part has 2 digits, 5 and 6 respectively. Calculate Digit Verification of CAS Registry Number 86869-56: (7*8)+(6*6)+(5*8)+(4*6)+(3*9)+(2*5)+(1*6)=199 199 % 10 = 9 So 86869-56-9 is a valid CAS Registry Number.