The CAS Registry Mumber 91034-24-1 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,1,0,3 and 4 respectively; the second part has 2 digits, 2 and 4 respectively. Calculate Digit Verification of CAS Registry Number 91034-24: (7*9)+(6*1)+(5*0)+(4*3)+(3*4)+(2*2)+(1*4)=101 101 % 10 = 1 So 91034-24-1 is a valid CAS Registry Number.