The CAS Registry Mumber 113478-77-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,3,4,7 and 8 respectively; the second part has 2 digits, 7 and 7 respectively. Calculate Digit Verification of CAS Registry Number 113478-77: (8*1)+(7*1)+(6*3)+(5*4)+(4*7)+(3*8)+(2*7)+(1*7)=126 126 % 10 = 6 So 113478-77-6 is a valid CAS Registry Number.