The CAS Registry Mumber 113525-71-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,3,5,2 and 5 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 113525-71: (8*1)+(7*1)+(6*3)+(5*5)+(4*2)+(3*5)+(2*7)+(1*1)=96 96 % 10 = 6 So 113525-71-6 is a valid CAS Registry Number.