The CAS Registry Mumber 76446-97-4 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 6 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 76446-97: (7*7)+(6*6)+(5*4)+(4*4)+(3*6)+(2*9)+(1*7)=164 164 % 10 = 4 So 76446-97-4 is a valid CAS Registry Number.