The CAS Registry Mumber 82176-65-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,2,1,7 and 6 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 82176-65: (7*8)+(6*2)+(5*1)+(4*7)+(3*6)+(2*6)+(1*5)=136 136 % 10 = 6 So 82176-65-6 is a valid CAS Registry Number.