The CAS Registry Mumber 143746-61-6 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,3,7,4 and 6 respectively; the second part has 2 digits, 6 and 1 respectively. Calculate Digit Verification of CAS Registry Number 143746-61: (8*1)+(7*4)+(6*3)+(5*7)+(4*4)+(3*6)+(2*6)+(1*1)=136 136 % 10 = 6 So 143746-61-6 is a valid CAS Registry Number.