The CAS Registry Mumber 153141-38-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,5,3,1,4 and 1 respectively; the second part has 2 digits, 3 and 8 respectively. Calculate Digit Verification of CAS Registry Number 153141-38: (8*1)+(7*5)+(6*3)+(5*1)+(4*4)+(3*1)+(2*3)+(1*8)=99 99 % 10 = 9 So 153141-38-9 is a valid CAS Registry Number.