The CAS Registry Mumber 76310-71-9 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,3,1 and 0 respectively; the second part has 2 digits, 7 and 1 respectively. Calculate Digit Verification of CAS Registry Number 76310-71: (7*7)+(6*6)+(5*3)+(4*1)+(3*0)+(2*7)+(1*1)=119 119 % 10 = 9 So 76310-71-9 is a valid CAS Registry Number.