The CAS Registry Mumber 125439-15-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,5,4,3 and 9 respectively; the second part has 2 digits, 1 and 5 respectively. Calculate Digit Verification of CAS Registry Number 125439-15: (8*1)+(7*2)+(6*5)+(5*4)+(4*3)+(3*9)+(2*1)+(1*5)=118 118 % 10 = 8 So 125439-15-8 is a valid CAS Registry Number.