The CAS Registry Mumber 125258-16-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,5,2,5 and 8 respectively; the second part has 2 digits, 1 and 6 respectively. Calculate Digit Verification of CAS Registry Number 125258-16: (8*1)+(7*2)+(6*5)+(5*2)+(4*5)+(3*8)+(2*1)+(1*6)=114 114 % 10 = 4 So 125258-16-4 is a valid CAS Registry Number.