The CAS Registry Mumber 120402-79-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,4,0 and 2 respectively; the second part has 2 digits, 7 and 9 respectively. Calculate Digit Verification of CAS Registry Number 120402-79: (8*1)+(7*2)+(6*0)+(5*4)+(4*0)+(3*2)+(2*7)+(1*9)=71 71 % 10 = 1 So 120402-79-1 is a valid CAS Registry Number.