The CAS Registry Mumber 4736-65-6 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 4,7,3 and 6 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 4736-65: (6*4)+(5*7)+(4*3)+(3*6)+(2*6)+(1*5)=106 106 % 10 = 6 So 4736-65-6 is a valid CAS Registry Number.