The CAS Registry Mumber 125918-55-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,5,9,1 and 8 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 125918-55: (8*1)+(7*2)+(6*5)+(5*9)+(4*1)+(3*8)+(2*5)+(1*5)=140 140 % 10 = 0 So 125918-55-0 is a valid CAS Registry Number.