The CAS Registry Mumber 143256-01-3 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,3,2,5 and 6 respectively; the second part has 2 digits, 0 and 1 respectively. Calculate Digit Verification of CAS Registry Number 143256-01: (8*1)+(7*4)+(6*3)+(5*2)+(4*5)+(3*6)+(2*0)+(1*1)=103 103 % 10 = 3 So 143256-01-3 is a valid CAS Registry Number.