The CAS Registry Mumber 84214-65-3 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,2,1 and 4 respectively; the second part has 2 digits, 6 and 5 respectively. Calculate Digit Verification of CAS Registry Number 84214-65: (7*8)+(6*4)+(5*2)+(4*1)+(3*4)+(2*6)+(1*5)=123 123 % 10 = 3 So 84214-65-3 is a valid CAS Registry Number.