The CAS Registry Mumber 120726-90-1 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,2,0,7,2 and 6 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 120726-90: (8*1)+(7*2)+(6*0)+(5*7)+(4*2)+(3*6)+(2*9)+(1*0)=101 101 % 10 = 1 So 120726-90-1 is a valid CAS Registry Number.