The CAS Registry Mumber 92731-76-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,2,7,3 and 1 respectively; the second part has 2 digits, 7 and 6 respectively. Calculate Digit Verification of CAS Registry Number 92731-76: (7*9)+(6*2)+(5*7)+(4*3)+(3*1)+(2*7)+(1*6)=145 145 % 10 = 5 So 92731-76-5 is a valid CAS Registry Number.