The CAS Registry Mumber 132507-77-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,2,5,0 and 7 respectively; the second part has 2 digits, 7 and 7 respectively. Calculate Digit Verification of CAS Registry Number 132507-77: (8*1)+(7*3)+(6*2)+(5*5)+(4*0)+(3*7)+(2*7)+(1*7)=108 108 % 10 = 8 So 132507-77-8 is a valid CAS Registry Number.