The CAS Registry Mumber 90093-40-6 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,0,0,9 and 3 respectively; the second part has 2 digits, 4 and 0 respectively. Calculate Digit Verification of CAS Registry Number 90093-40: (7*9)+(6*0)+(5*0)+(4*9)+(3*3)+(2*4)+(1*0)=116 116 % 10 = 6 So 90093-40-6 is a valid CAS Registry Number.