The CAS Registry Mumber 68877-50-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,8,8,7 and 7 respectively; the second part has 2 digits, 5 and 0 respectively. Calculate Digit Verification of CAS Registry Number 68877-50: (7*6)+(6*8)+(5*8)+(4*7)+(3*7)+(2*5)+(1*0)=189 189 % 10 = 9 So 68877-50-9 is a valid CAS Registry Number.