The CAS Registry Mumber 132680-58-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,3,2,6,8 and 0 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 132680-58: (8*1)+(7*3)+(6*2)+(5*6)+(4*8)+(3*0)+(2*5)+(1*8)=121 121 % 10 = 1 So 132680-58-1 is a valid CAS Registry Number.