The CAS Registry Mumber 126958-87-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,6,9,5 and 8 respectively; the second part has 2 digits, 8 and 7 respectively. Calculate Digit Verification of CAS Registry Number 126958-87: (8*1)+(7*2)+(6*6)+(5*9)+(4*5)+(3*8)+(2*8)+(1*7)=170 170 % 10 = 0 So 126958-87-0 is a valid CAS Registry Number.