The CAS Registry Mumber 123724-29-8 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,3,7,2 and 4 respectively; the second part has 2 digits, 2 and 9 respectively. Calculate Digit Verification of CAS Registry Number 123724-29: (8*1)+(7*2)+(6*3)+(5*7)+(4*2)+(3*4)+(2*2)+(1*9)=108 108 % 10 = 8 So 123724-29-8 is a valid CAS Registry Number.