The CAS Registry Mumber 111784-84-0 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 1,1,1,7,8 and 4 respectively; the second part has 2 digits, 8 and 4 respectively. Calculate Digit Verification of CAS Registry Number 111784-84: (8*1)+(7*1)+(6*1)+(5*7)+(4*8)+(3*4)+(2*8)+(1*4)=120 120 % 10 = 0 So 111784-84-0 is a valid CAS Registry Number.