The CAS Registry Mumber 185508-75-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,5,5,0 and 8 respectively; the second part has 2 digits, 7 and 5 respectively. Calculate Digit Verification of CAS Registry Number 185508-75: (8*1)+(7*8)+(6*5)+(5*5)+(4*0)+(3*8)+(2*7)+(1*5)=162 162 % 10 = 2 So 185508-75-2 is a valid CAS Registry Number.