The CAS Registry Mumber 125917-90-0 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 7 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 125917-90: (8*1)+(7*2)+(6*5)+(5*9)+(4*1)+(3*7)+(2*9)+(1*0)=140 140 % 10 = 0 So 125917-90-0 is a valid CAS Registry Number.