The CAS Registry Mumber 132870-72-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,2,8,7 and 0 respectively; the second part has 2 digits, 7 and 2 respectively. Calculate Digit Verification of CAS Registry Number 132870-72: (8*1)+(7*3)+(6*2)+(5*8)+(4*7)+(3*0)+(2*7)+(1*2)=125 125 % 10 = 5 So 132870-72-5 is a valid CAS Registry Number.