The CAS Registry Mumber 778511-13-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 7,7,8,5,1 and 1 respectively; the second part has 2 digits, 1 and 3 respectively. Calculate Digit Verification of CAS Registry Number 778511-13: (8*7)+(7*7)+(6*8)+(5*5)+(4*1)+(3*1)+(2*1)+(1*3)=190 190 % 10 = 0 So 778511-13-0 is a valid CAS Registry Number.