The CAS Registry Mumber 141243-55-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,4,1,2,4 and 3 respectively; the second part has 2 digits, 5 and 5 respectively. Calculate Digit Verification of CAS Registry Number 141243-55: (8*1)+(7*4)+(6*1)+(5*2)+(4*4)+(3*3)+(2*5)+(1*5)=92 92 % 10 = 2 So 141243-55-2 is a valid CAS Registry Number.