The CAS Registry Mumber 92303-90-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,2,3,0 and 3 respectively; the second part has 2 digits, 9 and 0 respectively. Calculate Digit Verification of CAS Registry Number 92303-90: (7*9)+(6*2)+(5*3)+(4*0)+(3*3)+(2*9)+(1*0)=117 117 % 10 = 7 So 92303-90-7 is a valid CAS Registry Number.