The CAS Registry Mumber 27177-02-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,7,1,7 and 7 respectively; the second part has 2 digits, 0 and 2 respectively. Calculate Digit Verification of CAS Registry Number 27177-02: (7*2)+(6*7)+(5*1)+(4*7)+(3*7)+(2*0)+(1*2)=112 112 % 10 = 2 So 27177-02-2 is a valid CAS Registry Number.