The CAS Registry Mumber 143260-21-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,3,2,6 and 0 respectively; the second part has 2 digits, 2 and 1 respectively. Calculate Digit Verification of CAS Registry Number 143260-21: (8*1)+(7*4)+(6*3)+(5*2)+(4*6)+(3*0)+(2*2)+(1*1)=93 93 % 10 = 3 So 143260-21-3 is a valid CAS Registry Number.