The CAS Registry Mumber 293305-78-9 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,9,3,3,0 and 5 respectively; the second part has 2 digits, 7 and 8 respectively. Calculate Digit Verification of CAS Registry Number 293305-78: (8*2)+(7*9)+(6*3)+(5*3)+(4*0)+(3*5)+(2*7)+(1*8)=149 149 % 10 = 9 So 293305-78-9 is a valid CAS Registry Number.