The CAS Registry Mumber 124641-97-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,4,6,4 and 1 respectively; the second part has 2 digits, 9 and 7 respectively. Calculate Digit Verification of CAS Registry Number 124641-97: (8*1)+(7*2)+(6*4)+(5*6)+(4*4)+(3*1)+(2*9)+(1*7)=120 120 % 10 = 0 So 124641-97-0 is a valid CAS Registry Number.