The CAS Registry Mumber 126087-58-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,0,8 and 7 respectively; the second part has 2 digits, 5 and 8 respectively. Calculate Digit Verification of CAS Registry Number 126087-58: (8*1)+(7*2)+(6*6)+(5*0)+(4*8)+(3*7)+(2*5)+(1*8)=129 129 % 10 = 9 So 126087-58-9 is a valid CAS Registry Number.