The CAS Registry Mumber 461420-93-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 4,6,1,4,2 and 0 respectively; the second part has 2 digits, 9 and 3 respectively. Calculate Digit Verification of CAS Registry Number 461420-93: (8*4)+(7*6)+(6*1)+(5*4)+(4*2)+(3*0)+(2*9)+(1*3)=129 129 % 10 = 9 So 461420-93-9 is a valid CAS Registry Number.