The CAS Registry Mumber 78233-12-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,8,2,3 and 3 respectively; the second part has 2 digits, 1 and 2 respectively. Calculate Digit Verification of CAS Registry Number 78233-12: (7*7)+(6*8)+(5*2)+(4*3)+(3*3)+(2*1)+(1*2)=132 132 % 10 = 2 So 78233-12-2 is a valid CAS Registry Number.