The CAS Registry Mumber 75649-64-8 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,5,6,4 and 9 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 75649-64: (7*7)+(6*5)+(5*6)+(4*4)+(3*9)+(2*6)+(1*4)=168 168 % 10 = 8 So 75649-64-8 is a valid CAS Registry Number.