The CAS Registry Mumber 82185-38-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,1,8 and 5 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 82185-38: (7*8)+(6*2)+(5*1)+(4*8)+(3*5)+(2*3)+(1*8)=134 134 % 10 = 4 So 82185-38-4 is a valid CAS Registry Number.