The CAS Registry Mumber 113520-78-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,3,5,2 and 0 respectively; the second part has 2 digits, 7 and 8 respectively. Calculate Digit Verification of CAS Registry Number 113520-78: (8*1)+(7*1)+(6*3)+(5*5)+(4*2)+(3*0)+(2*7)+(1*8)=88 88 % 10 = 8 So 113520-78-8 is a valid CAS Registry Number.