The CAS Registry Mumber 131703-60-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,1,7,0 and 3 respectively; the second part has 2 digits, 6 and 0 respectively. Calculate Digit Verification of CAS Registry Number 131703-60: (8*1)+(7*3)+(6*1)+(5*7)+(4*0)+(3*3)+(2*6)+(1*0)=91 91 % 10 = 1 So 131703-60-1 is a valid CAS Registry Number.