The CAS Registry Mumber 83125-45-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,3,1,2 and 5 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 83125-45: (7*8)+(6*3)+(5*1)+(4*2)+(3*5)+(2*4)+(1*5)=115 115 % 10 = 5 So 83125-45-5 is a valid CAS Registry Number.