The CAS Registry Mumber 120124-88-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,1,2 and 4 respectively; the second part has 2 digits, 8 and 8 respectively. Calculate Digit Verification of CAS Registry Number 120124-88: (8*1)+(7*2)+(6*0)+(5*1)+(4*2)+(3*4)+(2*8)+(1*8)=71 71 % 10 = 1 So 120124-88-1 is a valid CAS Registry Number.