The CAS Registry Mumber 127756-67-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,7,7,5 and 6 respectively; the second part has 2 digits, 6 and 7 respectively. Calculate Digit Verification of CAS Registry Number 127756-67: (8*1)+(7*2)+(6*7)+(5*7)+(4*5)+(3*6)+(2*6)+(1*7)=156 156 % 10 = 6 So 127756-67-6 is a valid CAS Registry Number.