The CAS Registry Mumber 131084-71-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,1,0,8 and 4 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 131084-71: (8*1)+(7*3)+(6*1)+(5*0)+(4*8)+(3*4)+(2*7)+(1*1)=94 94 % 10 = 4 So 131084-71-4 is a valid CAS Registry Number.