The CAS Registry Mumber 330795-80-7 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 3,3,0,7,9 and 5 respectively; the second part has 2 digits, 8 and 0 respectively. Calculate Digit Verification of CAS Registry Number 330795-80: (8*3)+(7*3)+(6*0)+(5*7)+(4*9)+(3*5)+(2*8)+(1*0)=147 147 % 10 = 7 So 330795-80-7 is a valid CAS Registry Number.