The CAS Registry Mumber 124223-08-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,4,2,2 and 3 respectively; the second part has 2 digits, 0 and 8 respectively. Calculate Digit Verification of CAS Registry Number 124223-08: (8*1)+(7*2)+(6*4)+(5*2)+(4*2)+(3*3)+(2*0)+(1*8)=81 81 % 10 = 1 So 124223-08-1 is a valid CAS Registry Number.