The CAS Registry Mumber 7522-64-7 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,5,2 and 2 respectively; the second part has 2 digits, 6 and 4 respectively. Calculate Digit Verification of CAS Registry Number 7522-64: (6*7)+(5*5)+(4*2)+(3*2)+(2*6)+(1*4)=97 97 % 10 = 7 So 7522-64-7 is a valid CAS Registry Number.