The CAS Registry Mumber 78287-42-0 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,8,2,8 and 7 respectively; the second part has 2 digits, 4 and 2 respectively. Calculate Digit Verification of CAS Registry Number 78287-42: (7*7)+(6*8)+(5*2)+(4*8)+(3*7)+(2*4)+(1*2)=170 170 % 10 = 0 So 78287-42-0 is a valid CAS Registry Number.