The CAS Registry Mumber 120417-39-2 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,4,1 and 7 respectively; the second part has 2 digits, 3 and 9 respectively. Calculate Digit Verification of CAS Registry Number 120417-39: (8*1)+(7*2)+(6*0)+(5*4)+(4*1)+(3*7)+(2*3)+(1*9)=82 82 % 10 = 2 So 120417-39-2 is a valid CAS Registry Number.