The CAS Registry Mumber 64695-83-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 6,4,6,9 and 5 respectively; the second part has 2 digits, 8 and 3 respectively. Calculate Digit Verification of CAS Registry Number 64695-83: (7*6)+(6*4)+(5*6)+(4*9)+(3*5)+(2*8)+(1*3)=166 166 % 10 = 6 So 64695-83-6 is a valid CAS Registry Number.