The CAS Registry Mumber 76447-88-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,6,4,4 and 7 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 76447-88: (7*7)+(6*6)+(5*4)+(4*4)+(3*7)+(2*8)+(1*8)=166 166 % 10 = 6 So 76447-88-6 is a valid CAS Registry Number.