The CAS Registry Mumber 84658-43-5 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 8,4,6,5 and 8 respectively; the second part has 2 digits, 4 and 3 respectively. Calculate Digit Verification of CAS Registry Number 84658-43: (7*8)+(6*4)+(5*6)+(4*5)+(3*8)+(2*4)+(1*3)=165 165 % 10 = 5 So 84658-43-5 is a valid CAS Registry Number.