The CAS Registry Mumber 124870-69-5 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,4,8,7 and 0 respectively; the second part has 2 digits, 6 and 9 respectively. Calculate Digit Verification of CAS Registry Number 124870-69: (8*1)+(7*2)+(6*4)+(5*8)+(4*7)+(3*0)+(2*6)+(1*9)=135 135 % 10 = 5 So 124870-69-5 is a valid CAS Registry Number.