The CAS Registry Mumber 117013-72-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,7,0,1 and 3 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 117013-72: (8*1)+(7*1)+(6*7)+(5*0)+(4*1)+(3*3)+(2*7)+(1*2)=86 86 % 10 = 6 So 117013-72-6 is a valid CAS Registry Number.