The CAS Registry Mumber 125918-06-1 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, 0 and 6 respectively. Calculate Digit Verification of CAS Registry Number 125918-06: (8*1)+(7*2)+(6*5)+(5*9)+(4*1)+(3*8)+(2*0)+(1*6)=131 131 % 10 = 1 So 125918-06-1 is a valid CAS Registry Number.