The CAS Registry Mumber 19380-33-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 1,9,3,8 and 0 respectively; the second part has 2 digits, 3 and 3 respectively. Calculate Digit Verification of CAS Registry Number 19380-33: (7*1)+(6*9)+(5*3)+(4*8)+(3*0)+(2*3)+(1*3)=117 117 % 10 = 7 So 19380-33-7 is a valid CAS Registry Number.