The CAS Registry Mumber 64945-52-4 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,4,9,4 and 5 respectively; the second part has 2 digits, 5 and 2 respectively. Calculate Digit Verification of CAS Registry Number 64945-52: (7*6)+(6*4)+(5*9)+(4*4)+(3*5)+(2*5)+(1*2)=154 154 % 10 = 4 So 64945-52-4 is a valid CAS Registry Number.