The CAS Registry Mumber 183382-76-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,8,3,3,8 and 2 respectively; the second part has 2 digits, 7 and 6 respectively. Calculate Digit Verification of CAS Registry Number 183382-76: (8*1)+(7*8)+(6*3)+(5*3)+(4*8)+(3*2)+(2*7)+(1*6)=155 155 % 10 = 5 So 183382-76-5 is a valid CAS Registry Number.