The CAS Registry Mumber 99304-29-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 9,9,3,0 and 4 respectively; the second part has 2 digits, 2 and 9 respectively. Calculate Digit Verification of CAS Registry Number 99304-29: (7*9)+(6*9)+(5*3)+(4*0)+(3*4)+(2*2)+(1*9)=157 157 % 10 = 7 So 99304-29-7 is a valid CAS Registry Number.