The CAS Registry Mumber 132087-55-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,2,0,8 and 7 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 132087-55: (8*1)+(7*3)+(6*2)+(5*0)+(4*8)+(3*7)+(2*5)+(1*5)=109 109 % 10 = 9 So 132087-55-9 is a valid CAS Registry Number.